The Original CZ Forum
GENERAL => CZ Gunsmithing => Topic started by: 75Plus on September 29, 2013, 03:03:17 PM
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For some time now it has been evident that assembling the barrel to the slide housing is not very consistent. Measuring the gap between the slide and the slide housing when in battery varied between .011" and .018" in the four Kadets that I have owned. See picture of the measurement on one of them.
(http://i944.photobucket.com/albums/ad289/AlveyJoe/Kadet%20Mod/GuagingTheGap_zpsdf3a7ba2.jpg) (http://s944.photobucket.com/user/AlveyJoe/media/Kadet%20Mod/GuagingTheGap_zpsdf3a7ba2.jpg.html)
With this condition the roll pin that secures the barrel in the slide housing is battered with every round. This leads to fractured roll pins in high round count units. Also, roll pins, being somewhat springy, could be adding to the light strike problem by absorbing some of the firing pin impact.
Three of the four units that I have owned have been modified to eliminate the gap. (I sold one before I knew of the problem.) Two of the three were modified with less precision than I am comfortable with but the results were satisfactory. Before doing the mod on my last Kadet, a full pistol, I put forth a bit of effort in developing a fixture that would guarantee positional repeatability to within .0005" (half a thousandth) The reason for this need for repeatability is that the barrel, in the fixture, must be positioned in the mill using the factory bored hole as a reference. Once this is done the gibs are locked to prevent table movement. The barrel can now be removed so the existing hole can be plugged and readied for re-drilling. When it is returned to the fixture I KNOW it is in the EXACT location as before. Now the mill bed can be shifted the necessary amount and the new hole drilled. The final step is to machine and fit a solid retaining pin to replace the roll pin.
The pictures show the fixture, the fixture with the barrel clamped in position and the setup in the mill.
(http://i944.photobucket.com/albums/ad289/AlveyJoe/Kadet%20Mod/HoldingFixture_zps422d45fa.jpg) (http://s944.photobucket.com/user/AlveyJoe/media/Kadet%20Mod/HoldingFixture_zps422d45fa.jpg.html)
(http://i944.photobucket.com/albums/ad289/AlveyJoe/Kadet%20Mod/BblinFixture_zps0ee6412f.jpg) (http://s944.photobucket.com/user/AlveyJoe/media/Kadet%20Mod/BblinFixture_zps0ee6412f.jpg.html)
(http://i944.photobucket.com/albums/ad289/AlveyJoe/Kadet%20Mod/Setup2_zps8ddb02c3.jpg) (http://s944.photobucket.com/user/AlveyJoe/media/Kadet%20Mod/Setup2_zps8ddb02c3.jpg.html)
(http://i944.photobucket.com/albums/ad289/AlveyJoe/Kadet%20Mod/Setup1_zps802e3b29.jpg) (http://s944.photobucket.com/user/AlveyJoe/media/Kadet%20Mod/Setup1_zps802e3b29.jpg.html)
Any questions?
Joe
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75Plus--yes, I have a question...How soon can you fix mine?
I am closing in on 25k rounds through this gun. Still functions perfectly and is very accurate.
I measured the clearance as shown above on mine after 300 rounds this morning at 0.012"
(http://joelynch.smugmug.com/Firearms/CZ-75B-2013/i-kTrgmrx/0/M/AA294576-M.jpg)
This gun functions very well, but there is definitely some peening at the breech face and barrel end where the two come together each time the slide cycles.
(http://joelynch.smugmug.com/Firearms/CZ-75B-2013/i-VbMXHS5/0/M/AA294584-M.jpg)
(http://joelynch.smugmug.com/Firearms/CZ-75B-2013/i-pZWQmWj/0/M/AA294581-M.jpg)
So, what do you think?
Joe
PS--video up in a little while on the range session this morning after installing your solid barrel pin. I also tried 15 and 13 lb hammer springs and included in the video is a spring swap at the range.
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Joe, I sent you a PM.
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75Plus,
You and I need to develop an extended Kadet FP . . . . . .
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I'll buy one.
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75Plus,
You and I need to develop an extended Kadet FP . . . . . .
Please, please, puleeze!!!
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75Plus,
You and I need to develop an extended Kadet FP . . . . . .
Count me in too!
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I want one too ! Excellent work 75plus !
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I'll take one of each!
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75Plus--What effect will a mushroomed breech face and barrel end have on the optimum redrill position? Will you have to smooth out the breech face and barrel face before you set the pin offset? In other words, what if someone sends you one that is already had the snot beat out of it?
Joe, the Kadet abuser
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75Plus - Is this a modification you would be interested in doing for the general public......more specifically ... me? If so ... please PM me I am interested.
Thanks
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75Plus--What effect will a mushroomed breech face and barrel end have on the optimum redrill position? Will you have to smooth out the breech face and barrel face before you set the pin offset? In other words, what if someone sends you one that is already had the snot beat out of it?
Joe, the Kadet abuser
I would think you might touch up the end of a badly mangled chamber end of a barrel but I would hesitate to do much to the breech face as that is where the head space is established for .22 rimfires. Reducing the depth of the cavity too much, which facing off would do, could lead to slam fires. From your pictures it appears that the barrel portion needs the most attention.
Joe
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75Plus,
You and I need to develop an extended Kadet FP . . . . . .
Agreed! I'd be in for 2.
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I's GET a Kadet Kit if I could just swap slides without changing the mainspring!
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The barrel can now be removed so the existing hole can be plugged and readied for re-drilling.
Any questions?
Out of curiosity, how are you plugging the original hole? A machined plug and/or weld? If it is a machined plug as it appears, do you have any concerns that it could rotate with the repeated battering it will take when the slide cycles? I presume you have thought of this and if not welded the plug is at least a press fit. Looking good and BTW I envy you having the equipment at your disposal to undertake these projects.
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The plug is a tight press fit, done in an arbor press. Fitting the plug is what necessitates removal of the barrel from the fixture. There is zero chance of the plug rotating.
Joe
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Even those just fairly tight solid pins on the75 hammers take a BIG hammer and quality starter punch just to budge 'them'. A fitted arbor pressed filler pin isn't going anywhere.
Even the pressed-on bearings on car alternators cannot be moved without an arbor puller---I found out the hard way years ago. :-[ ;)
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What would be the best material to make a new Extended firing pin out of? and what additional length should I look for on each side? Right now the hardest stuff I have on had is some stainless but I dont think this would be that great for a firing pin.... should I buy some s-7?
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What would be the best material to make a new Extended firing pin out of? and what additional length should I look for on each side? Right now the hardest stuff I have on had is some stainless but I dont think this would be that great for a firing pin.... should I buy some s-7?
At the beginning of the journey to find a better firing pin I considered the machinability of the material. I had some 303 stainless so I went with it. Stainless will suffice while in the development stage. Once a functional design is found a more suitable material can be chosen. I have some S-7 just waiting for the "Holy Grail" to be found.
Joe
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how does the extended firing pin work for ya? any better?
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how does the extended firing pin work for ya? any better?
I have seen some improvement but still not 100% which is what I am after. I think the profile of the tip may be a part of the solution. You can only vary it a couple of times before you need a new pin to experiment on. (The reason for free the machining material.)
A note of caution, the amount of extension is governed by the face of the chamber. If the new FP is too long it can, and will, peen that face when dry firing. Ask me how I know.
Joe
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Joe,
I still have that extended FP that you sent me on the bench, I just haven't had any spare time to finish it up and test it (I need to make a jig to keep the pin in the proper orientation for machining the chisel point first).
I plan to use it's dimensions to also make up a few lightened versions for additional testing.
I'm also going to try to find some lighter springs as well.
If we can get the Kadet to 100% reliability with a 13# hammer spring, it would make a lot of people happy!
Wish me luck!
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Joe,
If we can get the Kadet to 100% reliability with a 13# hammer spring, it would make a lot of people happy!
Wish me luck!
Understatement of the year. No reason to convert my 75 shadow to SAO. Always felt bad about throwing all of Stuart's hard work on the DA away with SAO.
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Has a lighter firing pin spring been considered as part of the solution?
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Without a firing pin safety block, one must be careful not to go too light with the firing pin spring. A little lighter might not hurt.
Joe
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Can't disagree Joe.
The Kadet is a range gun after all. It couldn't hurt.
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Kadets have been known to drop the FP keeper resulting in loss of FP and spring. A lighter spring may help this failure. In several cases of this that I have heard of the FP cavity had quite a bit of powder residue fouling it and slowing the return of the FP after firing.
So, that said, if you opt for a lighter spring, make sure you keep the cavity clean. Not doing so could result in a 3 item parts order!!!
Joe
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I guess that's a good reason not to do it.
Thanks Joe.
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For those who may be contemplating trying their hand at making an extended firing pin I made this sketch.
(http://i944.photobucket.com/albums/ad289/AlveyJoe/Kadet%20Mod/KadetFPMax_zps16eb4359.png) (http://s944.photobucket.com/user/AlveyJoe/media/Kadet%20Mod/KadetFPMax_zps16eb4359.png.html)
I made a tool to measure the distance from the chamber face to the shoulder in the pin cavity that stops the forward motion. The 2.038" noted in the sketch is the absolute max allowable.
The factory FP measures 2.022" so an extension of .015" is possible. Some have mentioned shortening the length of the max diameter portion to allow more FP travel. Just be aware that more than .015" removed from the tip side will get close to the peening region. Removing material from the hammer side will allow the hammer to contact the FP earlier and push it further but the tip starts further from the primer so that may be a wash. I have been trying different tip profiles with some success but no "Break Thru's." Still looking.
Joe
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Joe, I've shot .22 pistol for quite some time, and NOT DRY FIRING is a standard rule. Many name brands will peen when not inserting a case or a snap-cap before dry-firing. I used spent cases with dowell inserts for bullets back in the day with my High Standard..
If shooters know beforehand, why the concern IF it will improve the strike with a lighter spring?
"Warning, Dry-Fire without Snap-Caps Can Cause Damage to Your Pistol".
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Joe, I've shot .22 pistol for quite some time, and NOT DRY FIRING is a standard rule. Many name brands will peen when not inserting a case or a snap-cap before dry-firing. I used spent cases with dowell inserts for bullets back in the day with my High Standard..
If shooters know beforehand, why the concern IF it will improve the strike with a lighter spring?
"Warning, Dry-Fire without Snap-Caps Can Cause Damage to Your Pistol".
Don, I think dry firing has been a problem about as long as there has been firearms. Not sure about match locks or wheel locks but flint locks would be harmed by chewing up the frizzen and wearing out the flint. Then along came the percussion cap and dry firing them mushroomed the nipple so a cap would no longer fit. Next came the rim fires that would peen the chamber face. (Not sure about pin fires)
Yep, I agree with your warning 100% (Warning, Dry-Fire without Snap-Caps Can Cause Damage to Your Pistol") but "An ounce of prevention is worth a pound of cure"
Joe
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I fully agree that having your cake and can eat it too is best, but the "biggy" is getting a conversion that's NOT ammo picky---like my HS or the model 41s- or....... :D
I suspect you'll find a way to make it run. 8)
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For those who may be contemplating trying their hand at making an extended firing pin I made this sketch.
(http://i944.photobucket.com/albums/ad289/AlveyJoe/Kadet%20Mod/KadetFPMax_zps16eb4359.png) (http://s944.photobucket.com/user/AlveyJoe/media/Kadet%20Mod/KadetFPMax_zps16eb4359.png.html)
I made a tool to measure the distance from the chamber face to the shoulder in the pin cavity that stops the forward motion. The 2.038" noted in the sketch is the absolute max allowable.
The factory FP measures 2.022" so an extension of .015" is possible. Some have mentioned shortening the length of the max diameter portion to allow more FP travel. Just be aware that more than .015" removed from the tip side will get close to the peening region. Removing material from the hammer side will allow the hammer to contact the FP earlier and push it further but the tip starts further from the primer so that may be a wash. I have been trying different tip profiles with some success but no "Break Thru's." Still looking.
Joe
Thanks :-) I may just give it a shot. Thanks for doin all the research!
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I will shoot my 75Plus-modified Kadet early Sunday morning. Got the slide back today, just as planned. Will try the light hammer springs again, 13/15/17 lb, with the solid pin and the corrected barrel hole per 75Plus' original post here in this thread. Can't wait.
This is fun.
Joe
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Has this thread moved? I am intested in the Kadet Accuracy.
75Plus I sent you a PM.
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Hi.. Dying to know the conclusion. My 75B Omega Convertible is light striking on 3 out of 10 shots consistently. The Pin is clearly not denting the rim deeply. My Ruger SR22 leaves quite an indention...Thanks!
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I recently purchased a used CZ75 Kadet, and it has the problem of light strikes; 4-5 out of 10. First I found a shattered roll pin that holds the barrel in place; replaced with pressed in solid pin. Then I noticed that the barrel had shifted forward from the block/housing; the block that is pinned to the slide. The breach end of the barrel where the cartridge rim rest when struck was about .002" forward. How can that be prevented? I removed the barrel from the slide, and used a hard plastic mallet to lightly tap it back in place; so the end of the barrel if flush with the housing block. I went to the range today; had only about 10-20% FTF (Rem bulk). Most fired on the second firing; 2 would not fire at all after 3 or 4 tries. It still has the old style firing pin with the rounded point. What about cutting off a couple of coils of the firing pin spring?
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I recently purchased a used CZ75 Kadet, and it has the problem of light strikes; 4-5 out of 10. First I found a shattered roll pin that holds the barrel in place; replaced with pressed in solid pin. Then I noticed that the barrel had shifted forward from the block/housing; the block that is pinned to the slide. The breach end of the barrel where the cartridge rim rest when struck was about .002" forward. How can that be prevented? I removed the barrel from the slide, and used a hard plastic mallet to lightly tap it back in place; so the end of the barrel if flush with the housing block. I went to the range today; had only about 10-20% FTF (Rem bulk). Most fired on the second firing; 2 would not fire at all after 3 or 4 tries. It still has the old style firing pin with the rounded point. What about cutting off a couple of coils of the firing pin spring?
Put a 17# hammer spring in your pistol and try it again.
Joe
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If anyone is still concerned about the Kadet accuracy potential, I offer this target up for proof that the Kadet is limited only by ammunition.
I have maybe 7 clean targets but this is the only 10x, and it was in practice last year. I only had 40,000+ rounds through it at that time.
(https://photos.smugmug.com/Firearms/Pistol-Range-8-21-16-Ruidoso/i-xtQnLpK/0/dce22ffe/L/IMG_0652-L.jpg)
This is 25 yards standing single hand two strings of five shots in 20 seconds.
Joe
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Has anyone identified a competent gunsmith to perform this work?
I would like to get in touch with 75plus but I don’t have enough posts yet (I don’t want to post nonsense just to get numbers up).
If anyone could message me his contact information, I would appreciate it.
Thanks