Excerpt of light strikes quotes (CZF Kadet club posts)

[joerchi69]

Excerpt of light strikes quotes, missfire, firing pin, solutions, ideas, discussion, thoughts, concepts                     Part1

Every gun is a law unto itself                 
     line to prequote this cluster too.

To get a overview about what could cure the missfires i wildly copyd statements who sounded promising. When trawling through the kadet clubs data for hours, because of my kadets light strike odyssey (https://czfirearms.us/index.php?topic=104837.0) Let the quotes beginn:

testing dif. mainsprings
polishing FP channel, FP and FP spring
FP  heavyer
longer FP
reduce hit area of FP
choose hit area of FP on brass, avoid strongest brass area
---------------------------
Measure rim thickness.

let a gunsmith check the headspace, how much headspace is left with a round loaded in the chamber and the slide closed. The thought to it is, if the rimfire sits not tight against barrel face, the kadets firing pin can shove the cartidge forward and looses its momentum to ignite the primer on the first strike.

Then I looked closely at the fit of the slide as it closed against the back end of the barrel.  Bingo!  There was enough metal left at the back of the slide in the corners to prevent it from solidly and squarely locking up against the barrel.  If it didn't lock up tight, misfire happened.  A little work with a small file and my Dremel and the lockup was fine.  No more misfires.

first:  you need to make sure the hammer of your gun does not strike the top of the kadet kit when hammer is down,  some/most do with stock hammers (a .005"-.010") or so interference, the CGW race hammer not likely due to the 45degree back angle at top of hammer but I hand filed mine back a bit just in case of interference which was noted on the stock hammer.

second:  I backbored (end milled) the firing pin holding retainer clip .032"-.035", thus allowing a 'greater' transfer of energy time from hammer strike to drive firing pin forward.

third:  clipped/shortened the return firing pin spring by 2 or 3 rotations.

forth:  added apx .125" of pre-load to the CGW 13lb spring.

went to the local hardware store and bout some washers,  put them on the trigger 'stem' first then put the spring back in.. added a shim or two at a time,   put back together, try a magazine,    then do over until it was shooting 100%.  Still working at this time,  will try to get more round count down the barrel soon.

If your Delron bushing holds up... I'd love to purchase one from you.. I don't have access to all the tool/die machinery I used too, it was my initial thought to make a aluminum or copper bushing once I had a basic size/length to work from.

I also wish I hadn't missed purchasing a extended firing pin from CGW with a reduced return spring.

Those results are interesting, but keep in mind that a 13 lb/in hammer spring installed with spacers is a preloaded spring now closer to coil bind and is no longer rated at 13 lb/in from its new installed length.  Your shortened hammer spring will feel different in DA than it did before without the spacer when you put the centerfire slide back on.  Still interesting results, especially with the firing pin and retainer plate changes.

all good points.. glad everyone thinking a bit about this.. as of today,, 250 rnds.. no issues. first strike 100%.   yes, trigger is 'slightly heavier' than when 13lbs minus spacer. but the break is the same with a CGW race hammer, crisp, no creep. 

per my tool an die days... yes.. adds PRE-load tension.. and MAY shorten spring life (reasonable), but still is can be very effective in the right application.   


I really feel allowing a mere .032-.035" (thousands of an inch, to those not familiar.. human hair about .003-.004" thick) is the key here.  I haven't had time to check if I can go to .045" deep on backbore and then remove spacer.   seems interesting doesn't it w/ a stock CGW slightly pre loaded 13lbs spring?.    the transfer of energy is crucial to my mind.   allowance for transfer of kept energy via a slightly longer contact period b/t hammer and firing pin seem to be the key.. I can't get away from that aspect.   adding pre-load to hammer spring is a basic in tool/die performance day to day stuff... why over purchase a springs.. if a bit, small amount of pre-load works..   again.. maybe a 14lb or or a back bored retainer to .045 with a 13lb spring is the 'magic' ....  don't know..

I just know what I have works.. easily and fine.. replacement on main springs is relatively cheap. for what I get. reliable fire first strike on all .22lr ammo tried thus far..  and crisp break..

100prcnt with a 13lb CGW mainspring, a race hammer and some extra spacers/washers

On the phone, CGW said 17# would not be 100% without an extended FP (which they no longer sell). That is why I was thinking about the 18# or 19#, as the stock spring is 20#. But if it will not help SA, and will be minimal help for

I think CGW is being very  conservative.  I believe I've used the 17# spring with the factory firing pin and it works fine.  The springs are cheap from CGW or gunsprings.com (Wolfe) if you want to try one. 


the above responders now far more than I do ... however.. my current Kadet fires 100prcnt with a 13lb CGW mainspring, a race hammer and some extra spacers/washers added to the main spring...   current hammer pull is no big deal in DA.   in SA is a hard to  period.    have over 400rnds in Kadet with 100prcnt first hit firing at this time.  but I started with a gun close to 85-90prcent with the light main spring.

The 17# spring is the lightest you can run and get 100% ignition.  Try it.  It's only the first double action shot that is significantly affected by the hammer spring.  You can put in the CGW sear and hammer if you want a perfect single action trigger pull.  I did that to mine about 27k rounds ago, will shoot a bullseye match with it in 8 days.  Gun has 31k rounds through it.

A 15# will get you about 90% ignition.  We've tried all kinds of hammers, firing pin modifications, firing pin springs, etc.  There have been a few isolated cases where a 15 has worked more than 90% of the time, but the general result is that a 17 will always do the trick.  I converted mine to single action only and left the 17# hammer spring in the gun.   

The CGW hammer and sear will provide an absolutely excellent trigger pull for the springs you have to run.

Re: Reduced power hammer spring

Since you shoot bullseye, any other accuracy tips for the Kadet?

The 17# spring is the lightest you can run and get 100% ignition.  Try it.  It's only the first double action shot that is significantly affected by the hammer spring.

 Wolff sells 18# and 19# hammer springs, though. 

The true name for the major Upper part are:
"Slide Housing" (the main part that holds the Barrel and the Sights)

Yesterday i did 140 shots and had only 1 light strike ? with the 20lbs spring. And i blame that on the ammo

180 shots today without any issue!
That was the first time in 8 months and around 8000 rounds. :-)

Rhart:
I keep a Hoppe's BoreSnake handy, and run it thru every 100/150 Rounds
It tends to help with most failures

 I also have to add oil to the slide rails pretty darn often in the summer, like every 200 rounds or so.

In one Kadets I worked over made this clou a good deal:
At first I clipped the mainspring half coil by half coil to lighten the trigger pull. Side effect it is easier for the Kadet slide to run back and throw the empties because the hammer has not that much resistance than before.
I checked with all 22lr ammo I could get by and as the gun starts misfires due to too light hammer strikes I shifted a washer over the spring rod. This lifts the spring and was crucial for the gun to ignite each shell sure with no remarkable difference of light trigger pull. First come the washer, then spring and then the end cap with pin. You can vary the washers thickness until best results.
Acompanied with a polishing job at all lock parts and alterating the sear angle made all this a very soft, crisp and reliable gun whatsoever.

however,  you do NOT need to only have 17-19lb mainspring, I currently use a 13lb mainspring with a few added thin washers to add PRE-LOAD,  been 100% x 400rnds first strike.    Plus, contact CGW for a 'few' of the other non mentioned issues which can cause light strikes.!!
--
Does your bolt make contact with the housing at the front, or is there a gap?

See this post...http://www.czfirearms.us/index.php?topic=39826.msg221907#msg221907


no, my KK fits flush.. however I did reshape the guide rod projection to allow my KK to allow it to fit flush and bottom out.  That was done apx. 1.5 yrs ago when I started my my 'tweaking' of the Kadet to get reliable firing.

The other issue most don't look for, is to check to make sure the Hammer will actually lay flat against the striking surface.. some Kadets slide's are 'overbuilt' on that surface and don't allow for a full hammer strike and lay flat against the hammer pin/surface.

Re: 13lb/100%

Mine has a gap, but no signs of the recoil spring seat/guide rod projection being the issue.

Where did yours hit?

AND, contact Joe (75Plus) and see if he has any of his Stainless Guide Rods
You never know, you goota cut every little bit of drag you can   

first:  you need to make sure the hammer of your gun does not strike the top of the kadet kit when hammer is down,  some/most do with stock hammers (a .005"-.010") or so interference, the CGW race hammer not likely due to the 45degree back angle at top of hammer but I hand filed mine back a bit just in case of interference which was noted on the stock hammer.

second:  I backbored (end milled) the firing pin holding retainer clip .032"-.035", thus allowing a 'greater' transfer of energy time from hammer strike to drive firing pin forward.

third:  clipped/shortened the return firing pin spring by 2 or 3 rotations.

forth:  added apx .125" of pre-load to the CGW 13lb spring.

that is all I have done.

Very cool
It has been a long hard road for ANYONE to get even close to 100% with a light Hammer Spring

I stoned the rails on the Kadet

I figured out where my final little "hitch" is. It's actually occurring where the bottom of the FP keeper travels across the angled portion of the race hammer. It "hangs" up just a little bit in both directions of slide travel

 the Extended firing pin from CGW as well for insurance.

As Painter said;
Find the Lower you like best for it

Some have added Bolt / Slider Racker Studs to help with getting a grip on the thinness of the Bolt
Some have "tuned" their Ejector too

Maybe one of Joe's (75plus) Stainless Guide Rods
And one of Joe's KADET Firing Pin Service Tools
Keeping a Bore Snake and a "Tooth" Brush handy isn't a bad idea either

If I were to turn one, not only would I add a little to the Tip length, but I'd make the Hammer end as long as it can be and still allow for servicing  ( i.e. removing and installing the Stop )
yes was thinking longer tip, longer rear end.
if can figure out how to make the Kadet run with light hammer spring. that would be a game changer in all this.


Re: Extended Kadet Firing Pin

Stuart and Schmeky--I tested an extended pin and a light spring with both 13 and 15 lb hammer springs without total success, I'm afraid.  I would have to check my notes, but I think the 15 was good for about 90-95% firing and the 13 was not usable.   I went back to a 17 hammer spring.  I think that is correct. 

I would love to be able to use the same springs as for a competition gun, but I don't know how to do it.   
1st - You have to make sure that the barrel is location properly, so that the bolt impacts the slide, not the chamber end of the barrel.
2nd - Extended Firing Pin (for experimentation, it would be nice to have the same lengths but one standard weight and another lightened version.)
3rd - Reduced power firing pin spring
4th - (possibly) heavier hammer itself

It'll have to be a package deal.

Quote

Joe, that was my same experience when experimenting with your pin.

I had your longer pin, played with some reduced length firing pin springs, shadow hammers, and some TS hammers for weight. checked barrel play, etc.

still was not the reliability I wanted.

18lb ms in now to make the kadet 99%reliable

JoeL,

Good points and I listen.  I have given the Kadet EXFP much thought.  I have extended the hammer end, plus extended the opposite end as well.  However, the FP cannot contact the rim when the hammer is at rest.  I feel a sharp pointed angle on the rim-fire contact area is important.  Don't want to spread the inertia over to much area of the brass, but at the same time it can't be to sharp.

Lastly, the FP spring is a real bear.  So I did the calculations and the new FP spring should be the perfect working match for a 13# hammer spring.  As with all plans of mice and men, only testing will tell.

schmeky-
My new Kadet kit came today.
The firing pin has a slight bevel on one side.
Have you seen this?

If you look closely you will see that the bevel is at the bottom of the wedge of the FP. The area of the cartridge that would be contacted by the missing bit has little or no primer material so it is removed to concentrate the impact in the area that will do the most good.

22s and they run 99.999%
Yes, I do work-over all my Guns to get them as reliable as I can
So yes, I did stone the KADET Rails as smooth as possible (breaking all corners) without changing the dimensions
AND, contact Joe (75Plus) and see if he has any of his Stainless Guide Rods
You never know, you goota cut every little bit of drag you can


https://czfirearms.us/index.php?topic=60068.0

Wolfe Springs made it here today.  They make 22#, 24# and 26# extra power springs for the CZ.  Given the problems I have had, I decided to start with the 26# spring.  Its OD was snug on the ID of the main spring plug.  I grabbed a few spent cases to check how the fining pin imprinted with this setup.  It looks good.  Will try to get a range report thi


Zero FTF!

Ran 250 rounds though with no FTF issues.  150 Federal and 100 CCI Blazer.  The Federal ammo did give some failure to feed and some failure to eject issues, but no FTF.  I suspect the heavier hammer spring was holding the bolt back a little and did not allow it to cycle fully.  Keep in mind I did have the heaviest hammer spring installed (26#), but it lit off every round.  The CCI stuff did just fine.  So I guess the next thing to do is drop back to the 24# hammer spring to see if I still get zero FTF and eliminate the FTF and FTE issues with the Federal bulk stuff.

I did grab a bunch of spent brass and plan to look at it more carefully to see what variations in hammer strikes were occurring.  Will get back to the group later on what I find.

Here is the final geometry of the firing pin that is working for me.  I will also include the firing pin stop detail.  Basically the firing pin stop is just modified by slotting the top and adding the hole.

Here is the final geometry of the firing pin that is working for me.  I will also include the firing pin stop detail.  Basically the firing pin stop is just modified by slotting the top and adding the hole.


What strength hammer spring is it working with?

“Firearms are second only to the Constitution in importance; they are the peoples' liberty's teeth.”
George Washington

"A gun is like a parachute.  If you need one, and don't have one, you'll probably never need one again."

Right now I am using the Wolfe 26# extra power spring.

To recoup;
Modified CGW extended firing pin, wider front after filing, extended rear section by welding bead on (hammer now drives FP into rim rather than using inertia)
Added FP forward travel limiting spacer, FP can not protrude beyond headspace (not req'd if you make new F/P)
CGW light weight FP spring
Modified FP retainer to facilitate assembly with this firing pin
Modified bolt (hole added) to retain modified FP retainer to bolt
Added 1/16" roll pin to hold FP retainer in place
Wolfe 26# hammer spring


I guess I've lost track of where this is all going   ?
I thought the point of this exercise was to get the Kadet to run FTF(ire) free, using a low power (11, 13 or 15lb) Hammer Spring
I have been seeing 99.9% FTF free using Fed, 550 Bulk, running X-Power (in the B-SA Frame) and the Stock Hammer Spring (in the B-Frame), using the Stock Kadet Firing Pin with the Shoulders reduced as per previous Threads
All I used was my Micrometer, a Safety File and a Drill Motor / Press
After a nice CZ-USA Trigger Job, the Trigger on my B-SA (Lower) is breaking clean at < 3 lbs with an X-Power, 4 lbs with the Stock and 4.5 with the 15 lb HS
Go figure why it goes up when the Spring Weight goes down ?  ?

[joerchi69]

Excerpt of light strikes quotes, missfire, firing pin, solutions, ideas, discussion, thoughts, concepts                     Part 2


Jon, It appears that the Ruger firing pin has a wider and shorter foot print. The area covered is the same but is concentrated in the "Sweet Spot". Does this make sense?

There has to be a solution to this reliability problem. Sure wish that CZ would get involved!

It appears that the Ruger has a lot more area on the firing pin. I would think that compressing a larger area on the cartridge would improve the odds of firing if part of the problem was lack of uniformity in the primer deposition, or just getting more primer to ignite. Would increasing the size of the CZ pin striking face help? I presume doing so would lessen the depth of the strike, all other things being equal.

As an aside, you can see how the FP doesn't always strike at a perfect 90?.
I may order up another retaining plate and see if I can make it a tighter fit to hold the FP in the proper orientation.

To follow up on the Head Space discussion, I found the SAAMI web site which has the specs and technical drawings of the various cartridges. The link below will download a PDF file to your computer

 http://saami.org/PubResources/CC_Drawings/Rimfire/22%20Long%20Rifle%20-%20Sporting.pdf

Regarding headspace, the minimum given is .043" and the maximum is .051". Most of the measurements I have made as well as those from others appear near the minimum which, I would think, is a good thing. Imagine the trouble it would cause if they all ran to the maximum end of the spec!

The search continues.....

at still bothers me is the Ruger 22/45 never misses.  Its ignition system has the hammer pushing the firing pin into the rim.  I'm starting to think that the inertia concept that CZ uses (free flight of the firing pin after leaving the hammer strike) is not the best way to set off a rim fire cartridge.  I am in awe of those that say their Kadet kit runs just fine.

be a way to increase the dwell time the hammer has on the firing pin. Looking at the back side of the keeper one can see where the larger diameter of the firing pin rests against it. My thinking is that adding a little counterbore to allow the firing pin to move back into the keeper would do this. A .025" deep counterbore would almost double the distance the hammer was in contact with the pin. The next time I order tooling I will pick up a 6mm end mill and give this a try. The closes

schwererer FP
Wolfram

https://czfirearms.us/index.php?topic=60068.0

Page 18

engere Passung von FP zu FP channel - FP mit grösserem Durchmesser drehen damit
Trefferpunkt auf Rand an idealer Stelle bleibt

I feel if the FP body to FP bore clearance was tightened up to .002" - .003, and the FP tip was shaped differently, this could help.  However the crud you mention is an issue and only compounds the issue.

Steerclr, You need to recheck the size of the hole at the breach end. You are showing .089" but all the measurements of the firing pins the tip that runs through that hole is .091". This is the hole Dave (CGW) referenced in his recent post when he found the two specimens he measured had .100" holes which allowed .009" wiggle room.

JonNC, In a previous post you stated: "If you look at the right most case, notice how the strike isn't perpendicular?" The reason for this, or actually what allows this, is that the hole in the FP retainer is large enough for the FP to rotate somewhere around 15~20 degrees. The fix would be a smaller "D" hole in the keeper or a larger diameter at the hammer end of the FP. Neither option is as easy as it sounds.

I wonder what a little JB Weld in the D hole, or on the flat of the FP and a file could do?

It might hold long enough to see if it makes a difference. I think shrinking the D hole would be best as the keeper is forced against the FP as the recoil recocks the hammer. By shrinking the entire  hole that load would be distributed over a wider area. Just putting a little on the FP flat would not likely last long.

https://czfirearms.us/index.php?topic=60068.0

Page 19

Hei.
This is my solution With the light strikes on the Kadet. I made a New extended firing pin on the lathe, and modified the retainer plate a bit and drilled a small hole in in the slide to hold the firing pin in position. This is the same firing pin design as my Sako Triace machgun. I use a 13lb hammer spring and have not had a single malfunction or light strike since I did the modification. I have shot almost 1000 rounds without problems. I have tried to post some Pictures to explain, hope it Works.
The Kadet is lovely to shoot now.

https://www.dropbox.com/sc/1twrtupt0k6elbm/AABMGeg9fX3fDcc5qOE3rhSqa

Hi
The standard retainer plate is to secure the firing pin i position. With this mod. you have to open up the hole With a Dremel or drillbit so it is big enough for the New firing pin to go trough. The New firing pin is to long, so you have to slide the retainer plate i position first, then insert the firing pin. It is held in position With the small lockpin (look at the Pictures). I have used this mod almost a year, and have not had a single malfunction. I shoot  CCI standard. The hammer spring is 13lb. The gun Works Perfect
--

I've been thinking of what to do and here is a concept that uses a 1/16" pin to retain a modified firing pin retainer.  The firing pin is the CGW extended version with two modifications.  To limit forward travel the length of the large diameter section has been increased and a flat has been added to the top to allow room for the 1/16" retaining pin.  Softer CGW spring would be used. 

This would require to bolt to be modified by cross drilling it for the pin.  Disassembly would require the removal of the 1/16" pin. Original components could still be used with only the cross drilled hole in the bolt evident when restoring factory mechanism. 

Questions that arise are the hole clearance in the firing pin retainer so that when the hammer strikes it, it does not shatter the 1/16" pin holding everything in place. Also, is it best to use a roll pin or other method to retain that pin. Assembly steps would be drop in F/P spring, drop in firing pin and orient, slide firing pin retainer up, lock in place with 1/16" pin.

Assembly issue with shorter travel of F/P is addressed, F/P can no longer peen barrel, components flying off when F/P cycles has been eliminated, and hopefully I haven't put the crossed drilled hole through anything important. (I don't have the bolt with me to look at)

Let me know what problems anyone sees that may arise from trying this.

You must have a lot of free time on your hands while at work ?. Nice design but you've overlooked few major obstacles probably because the slide is not in front of you. If you increase FP retainer then you've to make room for it by cutting off the top of the slide/frame right up to the back of the rear sight (1/4") but even then there is nothing to put the retaining pin thru unless you extend/raise the end of the bolt (1/4") , which isn't a bad idea because it could be widened at the same time so there is more meat to grab on to when racking the slide. I see this as a factory upgrade when they make Kadet-3 or if a new bolt/slide is sold as an upgrade

Firing pin retainer is to scale and is factory size.  Only modifications were slot to clear F/P head and cross drilled hole.

The FP retainer plate only has less than .1" of metal above the FP so there isn't enough room to drill a hole for 1/16th retaining pin, unless your FP retainer is different size or I'm overlooking something.

How about a ball-detent under the firing pin retainer plate, the lower section below the firing pin, similar to what was done here for slide racker?

http://www.brownells.com/gunsmith-tools-supplies/handgun-tools/crane-tools/crane-ball-drilling-fixture-for-s-w-prod9849.aspx

(fromhttp://www.brianenos.com/forums/index.php?showtopic=108799 )


I put a flat on top of the F/P to add extra clearance for pin (0.0625" dia)  I made the assumption there would not be a lot of force on the retainer up/down although the hammer rides on the bottom.  I'm assuming the existing geometry handles it.   

As for retention I also thought of possibly using some set screws to retain the pin.

Thanks to everyone for looking and for the input.

TRGT,

A ball detent would be counter productive as there is about .005" clearance in the keeper slot. The hammer would have to overcome the spring pressure of the detent as well as launch the firing pin. I realize that this is not much but at this stage every little bit helps.

Steerclr,

Your assumption regarding the force on the keeper may be in error. The hammer is ridden down by the keeper. Note the radius on the bottom to facilitate this. You can also see also see a wear pattern on the largest diameter of the firing pin showing how the keeper is transferring this load to it. This may not be apparent on low round count Kadets but is very visible on the high count ones.

There may be a way to increase the dwell time the hammer has on the firing pin. Looking at the back side of the keeper one can see where the larger diameter of the firing pin rests against it. My thinking is that adding a little counterbore to allow the firing pin to move back into the keeper would do this. A .025" deep counterbore would almost double the distance the hammer was in contact with the pin. The next time I order tooling I will pick up a 6mm end mill and give this a try. The closest thing I have now is 1/4" which I think is too large.

Another thought for keeping the keeper in place would be to drill a couple of .050" holes, one on each side, on the edges, you have about .115" to work with, and put a bit of mono filament fishing line in them. Clip the line so that there is just a bit of pressure in the slot. This would help a lightened FP spring to hold the keeper while confining the modification to an easily replaced part. ( It would also maintain the ability to remove and replace the FP and keeper BLINDFOLDED  ? ? ) Actually the hole size is not critical, the size can be governed by the size line that one has available.
Joe

Great stuff guys.  Sometimes when I'm brainstorming I don't have the parts in front of me.  I was under the misconception that the top of the retainer rested against something on the bolt.  It is interesting that the firing pin takes the upward thrust load of the F/P retainer as it pushes the hammer down.  However this might still work.  If we use a clearance hole for the 1/16" pin in the F/P retainer and allow it to float, the firing pin flat on the bottom would still absorb the upward thrust of the hammer and the 1/16" pin would just keep the retainer from falling out.

Thoughts?

I'm the dummy here, but wouldn't the CGW FLOATING TRIGGER PIN DESIGN retain the pin and the plate?

I think if this is going to be a user upgrade it's got to be much simpler So how about this. Just make a U shaped bracket that would slide over the top with a retaining pin built and a set screw on each side. That way you can also add some material with serrations on each side of the slide to aid with racking. You would have to cut off 1/4" of the top slide to make room for it. This way you don't have to change anything and it would be a drop in upgrade. I wish I could add a detailed drawing but I hope you get my idea.


I decided since it was raining today I would try out my concept.  I cross drilled the bolt, slotted and cross drilled the retainer, and put the upper flat on the CGW extended firing pin.  It took a couple of hours and you need a mill, a collet fixture, and a carbide end mill for the firing pin flat.  Not a home type project.  I already had the spacers to limit the forward travel from before.  I put it all together and used the 1/16" roll pin to hold it together.  The  hole in the F/P retainer is 0.010" oversize for clearance.

Took it to the range to see if would work.  Good news is it didn't fall apart or show any signs of stress after running 150 rounds through it.  By the firing pin not being able travel forward as far as it used to and leave the retainer it always stays in contact with it to absorb the force of the hammer being cocked. I only had 1 FTF in 50 shooting CCI Blazer, but the federal bulk stuff still sucked at 1 in 10. I had several federal 22's that I couldn't light off no matter how many times they were hit, or if I turned them in the magazine and retried.  What still bothers me is the Ruger 22/45 never misses.  Its ignition system has the hammer pushing the firing pin into the rim.  I'm starting to think that the inertia concept that CZ uses (free flight of the firing pin after leaving the hammer strike) is not the best way to set off a rim fire cartridge.  I am in awe of those that say their Kadet kit runs just fine.

Good news is all the stock parts will fit back fine and the modification doesn't affect anything.

What hammer spring did you run?

The CGW light weight F/P spring was used.

I did just check and when using the CGW F/P, the end is in contact with the rim and does protrude from the bolt while the hammer is flush with the retainer. I will need to check how much it pushes out as compared with the Ruger 22/45.  Here is a photo of everything assembled.

The rollpin is metric, 3mm X 12mm long. You may be able to find one at your local hardware store or an auto parts store.

Follow-up on my previous post on firing pin weights;
Marlin (no return spring at all in this design) firing pin weighs 6.4 grams
CZ Kadet firing pin weighs 4.6 grams

Now I'm just wondering how light I can go on the firing pin return spring.  Somehow I think I need to get the firing pin to hit the rim harder.

Been there, done that on the lighter spring.  What happens is the FP stop plate will drop down ( oder anders befestigen, pin senkrecht bei FP wie in anderem Beispiel) and tie up the pistol if the FP does not return quickly enough after the inertial blow from the hammer.

Yeah, I was worried about using a light spring from reading previous posts.
? JonNC

One way to make the FP heavier, is to drill a hole in the back, pack it with tungsten powder and then plug the hole.
I'm not saying it would work, just saying that it's possible.

Does anybody know what steel the firing pin is made from?  I might be able to make one and elongate the large diameter shoulder and deepen the counter bore it fits into to add some mass?  I would first draw it up in a 3D modeling software to let the computer do the mass calculations and then decide if it is worth the effort.  Any thoughts?

Not sure WHAT steel it is but it SHOULD be S-7 for the job that it is doing. It would be hard to find a steel that handles impact and shock any better.

75Plus,
You are perfectly on point.  Most FP's are made from a readily available 0-1 or W-1 tool steel.  It works well as a FP material but does not have the impact resistance of S-7.

S-7 is the  very best FP material but is more expensive.  CGW's new Kadet extended FP's will be made from S-7, just like our center fire FP's.
S-7 is the  very best FP material but is more expensive.  CGW's new Kadet extended FP's will be made from S-7, just like our center fire FP's.

Here's an idea to add weight to the Kadet firing pin if that might help.

First image is stock pin  4.53gms
?
Next image is new pin  7.26gms
?
Here's an image comparing the two

[joerchi69]

Excerpt of light strikes quotes, missfire, firing pin, solutions, ideas, discussion, thoughts, concepts                     Part 3



If I made a heavier pin I would then have to bore the slide accordingly to allow it to fit.  Stock pin did protrude .035" on full extension and was .005" short of hitting the back of the barrel while staying in the recess of the slide.  So it seems it had plenty of forward travel available.  As an after thought  I did notice the Marlin firing pin had rounded edges and not sharp corners as does the CZ pin.  I was wondering aloud if it is easier to dent the primer than try to cut into it with sharp edges on the CZ pin?

A heavy pin will not accelerate as rapidly as a light one given the same hammer spring so the question becomes: will the heavy, slow, pin acquire enough energy to detonate the primer? (The hammer can only move it approx. .030") It may be hard to find the optimum balance between mass and speed. Modifying the slide for a heavy pin would be be the last item on MY list as once done it is irreversible. 
JMO
Joe 
I agree with 75Plus.  

If an extended FP does not remedy light strikes, I feel a simple milling cut at the top of the stationary upper slide may be a part of the fix.  The upper slide is a factor in how hard the hammer impacts the FP.  I feel a .015"-.020" cut may be just the ticket combined with a FP.  

A cut like this would not be expensive and done properly, you could not tell it was ever done.  

Well son-of-a-gun.  Received the prototype Kadet FP today.  It sure is pretty.  So, I did a comparison, same 22 ammo, fired in Kadet with the prototype Kadet FP/spring + 13# CGW hammer spring, then same ammo fired through a stock Ruger 10-22.  I then measured the depth of the FP impact, both measured precisely the same at .034".  So from all indications we have some seriously good impact characteristics in the Kadet with this new FP.

All rounds through the Kadet went off, all measured between .034" - .032" impact depth.  It's looking good.  So now I'll approve the prototype Kadet FP.  

Slide gap
I do have one question.  You talked about the forces exerted on the slide frame to barrel roll pin as being the energy transferred from the slide striking the back of the barrel, but doesn't some of the force transferred to the barrel then transfer to the slide stop pin and in turn to the frame? I realize there is some clearance in the slide stop to allow it to rotate, but it does index/fix the assembly in place.

You make a valid point, one that I failed to catch.  ?  However, by removing the gap and allowing the slide and slide housing to come together simultaneously with the slide contacting the breech seems to prevent further roll pin breakage. Could be this is an inertia induced problem.

Joe

After reading "steerclr's" post I spent several hours trying to understand how the roll pins were being shattered. During Happy Hour, while consuming my daily ration of the "golden pop with the foam on top", (for medicinal purposes only) I suddenly realized that the problem I identified and posted on Oct. 6 of last year could well be the cause. As "steerclr" correctly posted, the slide stop actually bore the brunt of the impact when the roll pin was mislocated. It does not, however, absorb any of the impact of the hammer slamming into the rear of the slide housing driving it forward into the roll pin. If the slide housing extends beyond the slide the hammer is arrested before the firing pin has been driven to its full extent causing light strikes. This also sends a shock wave to that little 3mm roll pin. This link is to the Oct. post,  

http://www.czfirearms.us/index.php?topic=58854.0

I would love to inspect the kits that "handgun2 and Franz Maurer" have as it sounds like they caught the Brass Rings !!!

Still looking!!

Joe

ell, the way I see it, there are so many issues coming into view that the odds of getting them all addressed is all but impossible
The Ammo issue being the largest of these
No two offering acts the same in any given Kadet....you'll NEVER solve this one
Just like Prime Hardness for Centerfires, 22s have different Primer sensitivities
Then there's the Short Pin vs Long Pin issue, Broken Cross Pin issue, Roll vs Solid Pins, Hammer vs Slide Off-sets....did I miss anything besides Stovepipes, Slide Stop issues and "No Lock Back" ?
It would be GREAT if you could run a 13# Hammer Spring in your Lower and switch from you Centerfire Upper to the Kadet Kit and back without messin' with the Springs every time
All I know is, my Kadet runs 100% with Federal Bulk on both my B-SA and my Stainless Lowers using Stock Hammer Springs
No, I don't have a sub 3# Trigger Pull, but they run GREAT
The way I see it;
If at first it don't go bang, cock the Hammer an try again
If that don't work, rack the Slide and bang away
If it happens WAY too often, try different Ammo first and feel happy that your Kadet is way less Ammo sensitive then a lot of other  Pistols out there
--

If I were to turn one, not only would I add a little to the Tip length, but I'd make the Hammer end as long as it can be and still allow for servicing  ( i.e. removing and installing the Stop )
yes was thinking longer tip, longer rear end. 
if can figure out how to make the Kadet run with light hammer spring. that would be a game changer in all this.
e along with a lighter spring if you could come up with a combo that would let me use even a 15lb hammer spring. I still get the occasional light strike with a stock hammer spring.

The heavy hammer springs also make the Kadet difficult to rack the slide with the hammer down
------------------

I've had this on the back burner for a while (sadly, making a living takes up my time lately).
Joe is right, the FP isn't a one part solution.

1st - You have to make sure that the barrel is location properly, so that the bolt impacts the slide, not the chamber end of the barrel.
2nd - Extended Firing Pin (for experimentation, it would be nice to have the same lengths but one standard weight and another lightened version.)
3rd - Reduced power firing pin spring
4th - (possibly) heavier hammer itself

It'll have to be a package deal.

I really wish I had time to mess with this...
Quote

Joe, that was my same experience when experimenting with your pin.

I had your longer pin, played with some reduced length firing pin springs, shadow hammers, and some TS hammers for weight. checked barrel play, etc.

still was not the reliability I wanted.

I will echo everybody else's comments.  If you guys can work out an extended fp/ spring combo to get us down to just 15lb main spring I would be all over it.  I have a 18lb ms in now to make the kadet 99%reliable, but really is a disservice to all of Stuart's hard work on the light DA pull. 

It's a go.  I have submitted the extended FP for some prototypes.  I am also having a dedicated Kadet FP spring wound for the new Kadet extended FP.

Might as well do it right the first time.  Goal is to have a reliable Kadet FP that will work with an 11.5# or 13# hammer spring.
re. 

I only get 100% reliability with CCI Mini Mags with the Kadet


Fellows, please remember that there are certain requirements to get a rimfire to light off.  David has to start this project with two constraints:  The ammo is a given and the hammer and hammer spring are fixed--people want to use their centerfire double acion light springs and hammers on a rimfire round.  There is only so much that can be done to the firing pin and firing pin spring.  You are still stuck with the energy from possibly a light hammer and most certainly a light hammer spring.  If anyone can do it, David can, but he is starting out with some serious constraints.  
= schwereren Hammer testen !

We almost need a striker fire modification to the Kadet bolt that would be released when the hammer hits what now is the Kadet firing pin, then you have to get the striker and the stock hammer cocked again for the next round.  Something like that.  May not be simple enough to be practical, however.  

All I'm saying is that the rimfire requires more of a whack than the centerfire and that whack has to come from somewhere and a 13 may not work regardless of what can be done to the firing pin.   But I hope David can come up with something.  Best I could do was 90% good ignition with a 15 lb hammer spring.  But we didn't try different pin tip widths and only one tip length, so maybe the combination exists and David can find it.    

Good points and I listen.  I have given the Kadet EXFP much thought.  I have extended the hammer end, plus extended the opposite end as well.  However, the FP cannot contact the rim when the hammer is at rest.  I feel a sharp pointed angle on the rim-fire contact area is important.  Don't want to spread the inertia over to much area of the brass, but at the same time it can't be to sharp.
After looking at the firing pin strikes of the Ruger, I  noticed they are shorter in length and concentrated on the rim. To concentrate the firing pin strike I have now increased the bevel at the bottom of the firing pin to shorten the strike length and direct the firing pin energy more toward the rim.  I also am cutting a couple of coils off the firing pin spring to reduce the preload weight on the firing pin.  I will try running the gun next weekend and let you know how it runs.  The Kadet kit is very accurate and a great accessory, I just want to get it to run cheap ammo like the Ruger.  FYI-I had very little FTF issues shooting CCI stuff.

Measured my Kadet 2 standard recoil spring;

Uncompressed 101.5mm (3.996 inches)

Compressed in gun (37mm hidden plus 10.5mm visible) 47.5mm (1.87 inches)
- as far as the slide will go back on the gun. Remove slide from gun, move slide to previous position and measure.

Measured pounds compressed to 47.5mm = 8 pounds
--
Comment
Author:
 
Vladka Svendova, CZ-SPARE.PARTS
Text:
 
Hello Jörg, regarding to your question about the forse of the spring 315817032002 .. in assembled condition 16,6 lbs and maximal operating 20,2 lbs.
Kind regards,
WWW.CZ-SPARE.PARTS - your online store
-----------------
about your problem. I had the same thing happen to me.
I called Ghost and Mike told me to put the original main spring back in. I did and also use CCI mini mags and no problem. For practice I use cheaper ammo. Once in a while I get a problem but when using rim fires there not 100%.
like I said, CCI Mini-Mags are the best.
---
I typically have 2-4 light primer strikes per magazine requiring an additional pull of the trigger. This happens with Remington and Federal bulk, American Eagle, and CCI MiniMag ammo. I figured that it mush have been my tuned trigger and light mainspring, so I put the original mainspring in with no difference in performance. CZ did send me a new firing pin spring/retainer awhile back after I informed them that my previous one was allowing the retainer to dislodge and spring back at me, so I suspect this is the result of a heavier firing pin spring. What, if anything, can be done to correct this? I have a match tomorrow and really wanted to run my Kadet, but this multi-strike thing is kind of annoying ?
Heavy hammer/main spring is the solution. I'm using 16lb + in mine with good quality ammo for great results.
I oil my rails with very light oil ( Hoppe's gun/reel oil which comes in the small container with needle applicator). I also oil the firing pin retention plate/hammer very lightly. I also add a few drops to the front of the slide that houses the recoil spring.  
  I'm thinking the slide (bolt) is moving a little slower in one frame than it is in the other.  Mine sometimes will not cycle if the ammo is too cold or needs oil, even on a well broken in frame.  There is just enough oomph in the standard velocity 22LR ammo to make the bolt cycle without anything to slow it down.  Add just a little drag or a weaker round and it won't always make it.  

I have a Ruger 22/45 that does the same thing--cool day or dry, won't cycle 100%.  Solution is always add light oil and warmer ammo.  

You will love the Kadet when you find the combination of ammo/lube that will let it run 100% in your frame. 

lp. I asked if it was new because it could have cosmoline/grease in the firing pin channel. Either way, remove the firing pin and make sure the channel is clean. This is a problem area on these guns as Joe L can confirm. Next, I'd try different ammo.

---
Milling an Extra Length FP with more exposed on the Hammer side of the Stop is a though
Adding more length to the firing pin is not an option. You can only make it just so long and still get the retainer plate back in. I have already added that amount. 
other note..... would it be possible to mill out the face of the firing pin retainer to expose a bit more firing pin and allow a heavier strike on the pin?
---

http://saami.org/PubResources/CC_Drawings/Rimfire/22%20Long%20Rifle%20-%20Sporting.pdf

Regarding headspace, the minimum given is .043" and the maximum is .051". Most of the measurements I have made as well as those from others appear near the minimum which, I would think, is a good thing. Imagine the trouble it would cause if they all ran to the maximum end of the spec!

following up on Schmeky's head space theory I made some measurements on the three Kadets that I have. One is a complete Kadet pistol the other two are kits, one a Kadet one and the other is a Kadet2. The pistol is from 07, the Kadet one from 09 and the Kadet2 from 2010. Both kits had a head space cavity .044" deep. The full pistol was the tightest at .043". Really not enough difference to cause a problem I would think. The overall measurements varied from date to date while the HS depth was close.

The pictures show my method of measuring for the head space. I started by using a digital caliper but it was hard to get consistent readings. Then I remembered having a rarely used 2 to 3" micrometer. The repeatability was excellent. I started by pulling the FP and keeper so I would have static surfaces to measure. I first measured the overall length of that portion of the slide that houses the firing pin. This is the longer dimension. I then moved to the bottom and slid the anvil of the mike into the HS cavity similar to how a round slides in. I then made that measurement and subtracted it from the previous one. If anyone has a better way I am open to suggestions.

As a side note: All three specimens showed that the hammer was coming to rest on the end of the slide housing. I have not determined just how much of the hammer fall was arrested by this but due to the short distance the hammer blow moves the FP any loss is important.

Here are the results by kit date.

Full Kadet '07 overall 2.281"  HS cavity 2.238"  HS = .043"
Kadet 1    '09 overall 2.278"  HS cavity 2.234"   HS = .044"
Kadet2     '10 overall 2.283"  HS cavity 2.239"   HS = .044


still bothers me is the Ruger 22/45 never misses.  Its ignition system has the hammer pushing the firing pin into the rim.  I'm starting to think that the inertia concept that CZ uses (free flight of the firing pin after leaving the hammer strike) is not the best way to set off a rim fire cartridge. 
Now that I realize the hammer actually drives the CGW extended firing pin into the case I was also wondering if the chisel point is a still a good idea?   On both the Ruger 22/45 and the Marlin lever gun the firing pins are much wider. Since I don't have any other rim fires to look at, I was wondering how it compares to other 22's out there?


Hammerkraft – schwerer Hammer
Another thing I noticed with the ext pin was the divot in the primer was actually deeper with my kadet kit versus my buckmark, but the buckmark has 100% reliability and the kadet has much lower, even with the deeper strikes. To me it is more an issue of transferring energy than depth of strike, at least for my situation.


FP stop fixate
FP fixate
https://czfirearms.us/index.php?topic=60068.0
19

With the Kadet blowback system, the only thing "locking" the bolt to the barrel is the recoil spring.
If one's Kadet has a weak recoil spring, that could cause inconsistent "lockup" which would affect how far the .22lr round is seated in the chamber.

In that case, it would have a similar effect to a primer that isn't seated all the way (first strike seats the primer, second strike ignites the round.)

Anyone happen to know the # rate of the stock Kadet recoil spring?

If we can determine that, we might be able to find some suitable springs to experi

way to go for an original thought!,   very interesting idea!,   so a slightly longer or stronger spring, with a longer firing pin ( thank you, CGW!), as well as removing the clearance issue on the hammer resting spot/per firing, and consistent ammo spec's. 

makes me wonder how strong a spring will work, and or any additional spring compression spacer might help?   again,   my kadet in the PO6 is/was almost 100%.

Could the stock spring be shimmed by thin washer/shims for a temporary test?Quote

JonNC 
Good idea to check every thing.  I did want to mention that the pictures you took of the spent cases were interesting.  When I looked at those impacted with the 13# hammer spring, they looked like mine hit with the 20# hammer spring.  So I am open to all ideas how to isolate the variables that are causing these issues.  I may head to my Dad's farm this weekend and let a few more rounds fly with my latest firing 

Here are my recoil spring measurements:

0.227" OD
0.0315 Wire Diameter
4" OAL
~52 coils.

According to an online spring rate calculator that should be a ~3.5# spring???

Can any spring gurus confirm that?

Does anybody know the Kadet recoil spring compressed length in the gun ?
(not the fully compressed length).

I measured 3.325". Might be +/- .010"

[joerchi69]

Excerpt of light strikes quotes, missfire, firing pin, solutions, ideas, discussion, thoughts, concepts                     Part 4


With the Kadet blowback system, the only thing "locking" the bolt to the barrel is the recoil spring.
If one's Kadet has a weak recoil spring, that could cause inconsistent "lockup" which would affect how far the .22lr round is seated in the chamber.

In that case, it would have a similar effect to a primer that isn't seated all the way (first strike seats the primer, second strike ignites the round.)

Anyone happen to know the # rate of the stock Kadet recoil spring?

If we can determine that, we might be able to find some suitable springs to experi

way to go for an original thought!,   very interesting idea!,   so a slightly longer or stronger spring, with a longer firing pin ( thank you, CGW!), as well as removing the clearance issue on the hammer resting spot/per firing, and consistent ammo spec's. 

makes me wonder how strong a spring will work, and or any additional spring compression spacer might help?   again,   my kadet in the PO6 is/was almost 100%.

Could the stock spring be shimmed by thin washer/shims for a temporary test?
------------------

JonNC 
Good idea to check every thing.  I did want to mention that the pictures you took of the spent cases were interesting.  When I looked at those impacted with the 13# hammer spring, they looked like mine hit with the 20# hammer spring.  So I am open to all ideas how to isolate the variables that are causing these issues.  I may head to my Dad's farm this weekend and let a few more rounds fly with my latest firing 
----------------------------------------------------------------------------------------------------------------------
Thanks for the specifications. It looks like our CZ 75 hammer springs (full size) will fit. The CZ 75 20 lb. (factory standard) spring we make measures as follows:
Wire - .045”
End OD - .264” & .262”
Body OD / ID - .258” / .168”
Length – 2.44 inches with 29 coils
 
CZ hammer spring page to review the springs we offer.
https://www.gunsprings.com/CZ/75%20Series/cID1/mID16/dID91#838

CZ 75 Hammersprings :

Reduced Power...: 15, 16, 17, 18 & 19 Lb.
Factory Standard.: 20 Lb.
Extra Power........: 22, 24, & 26 Lb.



Kadet Guide Rod plastic -  eine aus V2 drehen – make one of steel
check the recoil rod. many arrive from the factory with a slight curve. nuke the plastic rod in a microwave for 2 minutes in about an inch of water, and it will straighten out... you may want to roll it across a table to check alignment. this seems to help functioning.

Kadet kits I've purchased came with plastic guide rods that were quite curved right out of the box.  CZ-USA replaced the first rod a couple years ago with no questions asked, but this time they refused to replace the guide rod under warranty.
               The curved rod was causing the recoil spring to bind against the edge of the slide, making it more difficult to cycle the slide by hand, and no doubt retarding the slide's normal operation.
               Following another forum member's suggestion to heat the guide rod and attempt to straighten it I put the rod into a microwave-safe plastic cup, added about an inch of water and zapped it for 90 seconds.  When I poured out the boiling water I was surprised to find that the heat had caused the rod to return to its original, normal straight condition.
               Only time will tell if the fix is permanent, but for now the slide is working perfectly.
               If your Kadet guide rod is bent and you'd like to straighten it 
-------------------------------------------------------
Hi all, just wanted to pass along that I've had the light firing pin hits issue on my Kadet, but have found relief!

             After trying a lot of the great tips I've found on the forum I was still having a misfire every 3rd or 4th magazine regardless of ammo selection.  I decided to remove a small amount of material from the rear shoulder of the firing pin. This shoulder rests against the firing pin retaining plate limiting the exposure of the firing pin head to the falling hammer. I chucked the firing pin in my drill press and removed a small amount of the shoulder with my safe-edge file so as not to baunch up the firing pin head itself. Ultimately about .010-.015 was removed from this area. The result upon examing the re-assembled slide was a just noticeable amount of further protrusion of the firing pins head. 
The result in my Kadet was a big improvement in firing pin strikes.The fired brass now shows much deeper hits with great consistency. I have since fired about 600 rds of different ammo (Fed Bulk, Rem Bulk, Super Colibri) without a single misfire. This is on a CZ75B frame with a #17 Wolff hammer spring.

             Disclaimer: YMMV. Do not attempt if you're not willing to follow all appropriate safety precautions. Do not attempt if you're not willing to order a new firing pin if you @#$% up. Take off tiny amounts of material and test, repeat if nescessary. Don't try this at all if you're gonna blame me for anything!! lol. More is not better.

Hey thanks for the tip.It's always good to have an alternate ideas to fix this problem.

I was getting my Kadet ready for another range trip and thought I'd give your fix a try. I've been having light strike issues again. Well, I didn't have your post with me in the shop, so I inadvertantly filed some off the place where the firing pin is stopped from going further. That would be the other end of the raised portion of the pin from where you were filing. My firing pin doesn't stick out the back any further, but does go out the front just a bit further. The amont I removed with a very fine file is about what you would call a good polish. This seemed logical to me as I looked at it. Didn't take much off at all.

 Good news is that it seemed to help. I used some of the dreded Remington thunder duds. Shot about 300 of them. Had very good strike marks on the brass and very few duds. Out of the 10 or so I only got two of them to fire in my ruger. The others were total duds. This is real progress.

I chucked the ole firing pin in the drill press today and filed 10 thousands off the shoulder that rests on the retaining plate,(the part that holds the firing pin in). I measured the shoulder area before and after the mod. no failures so far. the strike on the case is a lot more pronounced than is was before. .010 doesn't sound like much but it's just enough to give the pin the extra inertia that it needs.

Just wanted to add that I went a different route and installed a wolf extra power mainspring.  While this does increase the double action pull weight, I couldn't tell any difference in the single action pull and it hits .22 brass like a sledge hammer.  I have not had a .22 round misfire in I don't know how long.

Measure rim thickness.

Check Schlitten an Lauf – Sitz  Check slide to barrel
Check slot u. Extractor  ohne Kontakt

  Upon examining my slide I noticed that it wasn't fully seating against the barrel when the hammer was cocked, thus inducing too much headspace. Excessive galling had also occured between the mating surfaces. 

 had a new experience the other day, when shooting with CCI Stingers. Not every time, but very often, the firing pin stop (#56 in diagram, in manual) hooked itself onto the hammer, when the slide is retracted by the recoil.
 After a head-scratch and oogling into the chamber to see if the ejector (#47) was broken, I noticed the slide stop had slid down, so far that the back end of the firingpin did not protrude through the hole in the firing pin stop. In the event of the slide going forward again, to feed a new bullet into the chamber, it would never go further, than having the firing pin stop jam itself onto the hammer. Frustrating. ? 

 My diagnose to this problem is, that when shooting Stinger, the firingpin-spring is to weak, so it isn't able to follow the slide fast enough, making it possible for the stop to fall down. I am in need of a stronger firingpin-spring to avoid the problem, right?
Although, then i have to consider the opposite problem, If I choose to shoot 'standard', i.e. weaker, ammunition.

 Is there anyone that has found a good alternative solution to this issue? Of course, welding the part to make it stick is no good solution. ?

  Judicious use of Loc-tite? (I suspect just a little dab'll do you.)

            I'll consider having a gunsmith machine me a part that fits better. Perhaps there is a possibility to modify the slits, where the stop sits. I was thinking of making the stop, with a 'fin' on each side, so the stop only can be dropped into the slits from the top. Then I at least would avoid having it drop further down. I believe this would make the pistol more reliable when shooting powerful ammunition, without having to change the spring, which would likely lead to experiencing misfires with softer ammunition. -Or am I wrong?

            First I flattened and cleaned the mating surfaces with a file so that they would perfectly mate. At this point I discovered that the ejector (see picture) was pushing the slide away from the barrel, thus inducing excessive headspacing. 
            To remedy this required "ajustment" of the extractor-to-barrel slot correction. The extractor pushed the slide back with a lot of force. I first filed the barrel slot as much as I could before cutting into the chamber area. I then filed back the angle on the mating surface of the ejector until it mated completely with the barrel slot. 
            To function properly the slide must firmly seat against the barrel when you pull it back about 3/16". If the ejector still pushes the slide back you will still have problems.
            I tested my CZ today and shot over 200 rounds of Winchester Wildcats with no misfires and one stove pipe. Awesome!!!
            Prior to my "adjustments" I would get about 4 -6 misfires and about 2-3 stove pipes per 10 shots.

I took the firing pin out of my kadet and inspected it for smoothness.  It had lots of fine lines around it's circumference from the lathe.  I took some 600 grit sandpaper and smoothed it up and then finished with 0000 steel wool.  What I noticed was that with the spring removed and the firing pin and slide stop inserted, it dropped more smoothly after the modification.  I also used compressed air to clean the firing pin channel in the slide.  I believe this modification may reduce the percentage of light strikes that I have experienced.  I had been getting several per hundred with some ammo.  I have one box left of really lousy blazer ammo I'm going to use to test my kadet for reliable ignition.   Stovepipes however are a thing of the past.  mapdude

[joerchi69]

Excerpt of light strikes quotes, missfire, firing pin, solutions, ideas, discussion, thoughts, concepts                Part 5




Solve your Misfire problems...

I'm still getting light strikes after testing several hundred rounds.  I noticed that the trigger stop on my CZ 85 was set so I wasn't getting a perfectly clean hammer release.  More work and testing to follow. mapdude

I still seem to have intermittent ignition problems with my Kadet and I can't figure out where my problem is occuring.  I'm getting what seems like freqent light strikes.  I Traded out the firing pin spring with a lighter one and it didn't make any difference.  Any ideas?  I'm wondering if the way the rear plate holds the firing pin in place has anything to do with this.  It's a bit loose fitting on my unit.  Mapdude

also check after a missfire that your slide is shut all the way, a partial open slide will have a weak strike so see if you can send it home after a missfire and if it shuts closed. you will have to figure out what is keeping it from closing all the way, usualy dirt or a burr or a weak spring. also not enough lube or slide sticking.

hell seats freely, smoothly and totaly.  IF the shell isn't seated firmly, the hammer's strike energy is absorbed by the shell moving forward and follow up strikes may result in a fire.  You didn't state if you tried multiple strikes on the duds.  I'd polish the feed ramp and chamber a bit with a dremel and see if a live shell seats into the chamber. 

Range report.
  Installed a Wolff 24# hammer spring.Removed 2 coils from firing pin spring.Headed to the range yesterday.Results:
  Federal bulk ammo:15 FTF out of 200 rounds,all but 4 fired on second strike.
  Federal auto match: 200 rounds,no FTF.
  CCI mini mags,100 rounds fired,no FTF.
 Very happy with results but disappointed with quality of the Federal bulk.Will have to stick with the better quality ammo.Pistol is very accurate with anything that will fire in it.Thanks for all the help.

 Also, keep the firing chamber clean!  If the shell is not firmly seated the energy from the firing pin strike will be absorbed with the small movement of the shell forward. 

so far is order Wolff replacement mag springs

How can a firearm cause a misfire due to an insufficient indent? One possibility is a damaged firing pin, one that has either a bent or chipped tip. Another possibility is that the firing-pin spring is too weak. The spring may be dragging on the interior of the bolt body or impeded by grease in the bolt, especially under cold conditions. The pin may be dragging on an improperly aligned firing-pin aperture, or it may be too short. Misfires can even be caused by excessive headspace. Basically, headspace is the measurement from the slope of the shoulder to the base of the cartridge, or the corresponding dimensions in the rifle chamber. Excessive chamber headspace allows the cartridge to be farther forward in the chamber away from the firing pin, or it can allow for the cartridge case to move forward when struck by the firing pin. Certainly, this can affect ignition reliability and cause misfires.

I had Mike at CZ-KC do a trigger job on my 75B-SA and it came back with an average trigger of 4.0 lbs
BUT, it wasn?t reliable (lots of FTF) with my Kadet kit any longer
So I put a Wolff, Extra Power 22 lb hammer spring in and a very odd thing happened
Now I got a 3.8 lb trigger and the break seems a lot crisper
Who knows? ?

So far, I've lightened the fp spring, slightly reprofiled the chisel tip of the fp narrower, and filed a groove in the fp retaining tab at the back to allow the hammer a better hit on the fp.  That's improved things, but it's still not nearly reliable.

Hard to tell by looking at the springs what #'s they are.  Just buy a calibration pack containing 4-5 springs from 16-20#'s and try the minimum #'s that fires the gun consistently.   For me that is 17 #.


https://www.rimfirecentral.com/forums/showthread.php?t=1059114

I did stone and sand with 600 grit sandpaper to clean the burrs and gouges off the mating surface where the pin fits along the bolt so it would slide back and forth smother. I found a burr that shaved off inside the bolt housing and figured the ruff surface was the culprit of the FTF issue. After I cleaned the pin I took it out yesterday and put 50 plus rounds through it with no ignition issues

We have two RAR in .22 LR. They both hit too far inboard, in the same position as yours. From what I've seen from the benchrest crowd for the best ignition the indentation should go clear to the OD (outer diameter) of the rim because that is where the priming compound is concentrated and will actually get a solid whack.


I was having problems with my Kadet Kit.  I was getting about 3-5 failures to fire per magazine which was actually getting worse with use since new.  It would always fire on the second trigger pull but I was getting tired of the click and no bang.  I disassembled the firing pin mechanism thinking that the pin may have been dirty enough to affect the strikes.  Lo and behold, the pin was fairly clean.  I then started testing the firing pin fit in the slide and the fit  of the hammer end of the pin in the firing pin stop.  I noticed that the machine marks on the hammer end of the firing pin were "hanging up" on the tool marks in the hole drilled in the firing pin stop.  I put some Mothers Mag and Alumunum Polish on the firing pin where it fits into the firing pin stop and worked the pin back and forth against all the interior surfaces of the firing pin stop(maybe 10 minutes) until the worst of the roughness was worked out.  I then assembled the kit, mounted it on a frame and took it out and shot it.  Bingo! that was the problem.  ?   The roughness of both the firing pin and where it fits the hole in the firing pin stop was enough resistance to overcome the hammer drop and keep the round from going off. 

Make sure your Bolt is going ALL the way into Battery
One thing you can try (and it worked for me) is take couple thousands off both sides of the Firing Pin Shoulder
I took 0.02 off of the front and 0.03 off of the rear

This gave me more exposed Pin and a bit more overall travel
Hope this helps yours, like it

Not sure what the firing pin striking end looks like, but if it's too blunt it will cause miss fires.  I always make sure my rimfire firing pins are chisel-shaped with a narrow striking end.  HTH

A maximum power mainspring is not required for a properly functioning Kadet slide.  I suspect you have something wrong with the firing pin or firing pin mechanism.  Make sure there's no gunk/build up in the firing pin chamber (sounds like you have).  A quick call to CZ will probably get you a replacement firing pin in the mail.  Install that and see if you experience the same problems.  I doubt you will.
I did try taking some off the rear shoulder, but I dont' suspect it's a prime problem because with multiple hits on a dud bullet (I did have quite a few of duds with a box of federal ammo that I bought for testing) the pin strike depth on the back of the bullet is fairly significant.. nearly cutting through. So I think the pin has the ability to extrude enough.
I have even filed the firing pin stop down a few thousandths were the hammer strikes it so that it could maybe transfer just a little bit more energy to the pin... there is a limit to how much this can be done as I don't want other parts of the gun (frame, etc) to take the impact of the dropped hammer.

I checked the slide going into battery,, between each shot push the slide forward to make sure there was no extra 'click' .. the breech face and the slide face are definately mating together. I double check by pulling the slide back a bit to see if the bullet is also being pulled out as well.

I've even considered heating the firing pin up to red hot and hammering it out a little longer (gotta be careful of the shoulders),, but I don't necessarily have the tools for this, I might would have better luck cutting the pin and installing a threaded portion (with loctite) to 'extend' the pin a bit...

At this point I'm just wondering if maybe the milling tolerances on the slide and/or barrel I got were just the one in 1000 that were a bad match. .. speaking of that, the recoil spring retainer cup pressed into the slide came out on mine.. it goes back in and with the spring stays in easily, but It's just one more little problem on my copy.

I've got another firing pin on order, along with extra springs all around. I was going to wait till they came in and I had an opportunity to test them and then I'll call up CZ and see what they can do. Matt Mink lives nearby; if he has time, I may drop it by his place to see if he can do better with it than me

Yeah, the Recoil Spring Housing has been known to do that
It's a press fit and then Stacked in place
You can press it back in with a little Black Max Loctite around it and it'll never happen again
I wouldn?t dick around with trying to stretch the Firing Pin
Bite the Bullet (no pun) and call CZ-KC before doing that

on a good note,, CCI Stinger and Mini Mag HP seems to run through it with little to now problem.. none on the 10 shot tests strings I did at least. Federal automatch is on par with winchester western.... click click click boom.

on a seperate note, CCI Stinger really is some hot stuff.. white fire out of the barrel and all... and it stings like a mother when the shell lands in your collar .. I have a second degree burn from one shell
fun stuff though

It might all be because of ammo after all

Use a Q-Tip and give the FP Hole a good cleaning, then blow it out with pressured air

The Fail to Eject could be tied to the Slide being stiff and not moving fully or fast enough to the rear
As for the slide being stiff;
Try installing the Kadet Upper without the Recoil Spring and no Magazine
See if it moves freely and fully to the rear and back into Battery
If there no issue, try it with a Magazine inserted and try again
If there is an issue with the Slide, it should be easy enough to feel / find it this way

failure to eject and the slide seems stiff

A possibility is the polycoat was over-sprayed and is in the rails causing sluggish movement of the slide. That can even result in failures to fire by preventing the slide from coming back into battery firmly enough. The cartridge needs to be seated with a little force because rimfire chambers foul quickly. The Kadet can be fired with the slide slightly out of battery, which will result in light strikes.

The over-spray of the poly coat prooved to be the problem in a similar case on another board. The upper was sent back back to CZ USA and that was their diagnosis. Of course it was fixed for free.

I guess I've been lucky. My Kadet 2 kit on top of my 75B frame will cycle and fire everything including Wolf MT, CCI SV,  Rem sub-sonic, Fed or Rem bulk now that it's had a good break in. I use the stock 75B mainspring.

I've converted my gun to SAO, so using a heavier main spring isn't a big deal for me. Thanks for the help guys!

I mount the Kadet Kit on my B-SA a lot
I replaced the Hammer Spring with an Extra Power Spring
It pops the Rimfires (and 9mm)100% and I found that my Trigger breaks with a lighter pull now
ran a sao 75b with a Kadet. set up with a 17# mainspring, trigger was at 2.5#. ran 100% reliable with CCI green tag, CCI minimag, remington Thunderbolt, Fed 550 pack ammo and Winchester bulk pack ammo.
with a 16# mainspring, reliability dropped off.

[joerchi69]

Excerpt of light strikes quotes, missfire, firing pin, solutions, ideas, discussion, thoughts, concepts                Part 6


another note..... would it be possible to mill out the face of the firing pin retainer to expose a bit more firing pin and allow a heavier strike on the pin
n my ongoing search for the secret to touching off the .22 rimfires with a #13 hammer spring I repinned the barrel of my full Kadet and made an extended firing pin. Test firing was disappointing. I reprofiled the FP tip a couple of times but saw no change. THEN I noticed something that was not as it should be. There was plenty of evidence that the hammer had been contacting the end of the slide housing, the fixed part of the upper, but practically no sign of contact with the FP retaining plate. With the hammer down, resting against the housing, I could move the slide slightly to the rear before the retainer contacted the hammer. The hammer was being stopped short.

Adding more length to the firing pin is not an option. You can only make it just so long and still get the retainer plate back in. I have already added that amount. My Kadet 2 kit does not have the problem nor does Joe L's Kadet 2. 

on another note..... would it be possible to mill out the face of the firing pin retainer to expose a bit more firing pin and allow a heavier strike on the pin?

chucked the firing pin in my drill press and removed a small amount of the shoulder with my safe-edge file so as not to baunch up the firing pin head itself. Ultimately about .010-.015 was removed from this area. The result upon examing the re-assembled slide was a just noticeable amount of further protrusion of the firing pins head.

The result in my Kadet was a big improvement in firing pin strikes.The fired brass now shows much deeper hits with great consistency. I have since fired about 600 rds of different ammo (Fed Bulk, Rem Bulk, Super Colibri) without a single misfire. This is on a CZ75B frame with a #17 Wolff hammer spring.

Regardless of the spring test, I am confident that the solid pin addition will help in maintaining accuracy and consistency in this pistol.  I think my roll pin has been broken for a long time.  There have been 3 or 4 times during the year when the sight elevation needed to be corrected by 4-6 clicks and I never figured out why, then I would have to change it back.  My bet is that the barrel moved vertically due to the broken pin each time, changing the sight versus barrel alignment. 

What I did was remove half on both sides of the Shoulder, approx 0.007+/- each
I get zero light hits now

The top picture is my Kadet Kit and shows the gap between the slide and slide housing. The lower picture is the upper from my full Kadet and shows the two slide parts in contact with each other. After the repair that I made to the kit the two look the same. BTW, I call this a repair not a modification as what I did should have been done during manufacture. The QC on the Kadet line has lots of room for improvement.


Check your manual and see which recoil spring you have in the slide and which one is still in the box.  Swap the recoil spring to the stronger one if it isn't already installed.  That may help get the slide in to battery and minimize the light hit problem.  Different ammo should definitely be tried.  Also make sure the chamber is clean.  Make sure the extractor isn't hanging up at the notch in the barrel when the slide comes forward.  Sometimes the extractor can hang slightly on the barrel. 

Can't be much more help until you try something different.  Once it is running OK, it will run forever if you clean it every 700-1000 rounds and change the recoil spring periodically.  Mine has 24k rounds through it.

75Plus has my slide right now.  He is going to re-do the pin hole in the barrel so that the load on the pin is minimized.  I was surprised that the 15 worked perfectly last Sunday after putting in the solid pin.  Last time I tried the 15, the failure rate was 10% or so for 1st hit fires.  The 13 lb hammer spring fired everything eventually, but many took 2 strikes.

Try some different ammo first.  CCI Mini-mags or Golden Bullets seem to work pretty well.  If there are still problems, then something else is the problem.  Usually an 18# spring will work fine.  Is there a chance the spring in that frame is lighter?  If so, try a new spring, anything 17 or over.

Is this a new Kadet Kit or used and did it work fine on other frames?  If it worked OK before or on other frames, then maybe the problem is in your frame.  Does this frame work fine on all centerfire ammo?  Hammer isn't dragging on anything, no obvious friction issues? 

Excerpt of light strikes quotes, missfire, firing pin, solutions, ideas, discussion, thoughts, concepts                Part 6


The fact that you mentioned several failure to feed might be a clue.  Any chance the slide isn't completely in battery causing the mis-fire?  If so, clean the chamber really well and try it again.  If the round won't seat completely in the chamber, then the firing pin may hit the rim but not hard enough to seat the round and dent the rim hard enough to cause ignition.  I've had this happen if I let the chamber get too gunked up between cleanings. 

If the recoil spring is too weak to chamber the round and get the slide back in to battery, then replacing the recoil spring may be all that you need.  If it is a new kit, you may have one in the box, if so, try it. Maybe this will give you some ideas. 

PS, I never put any oil on the firing pin or in the firing pin channel.