light strikes FTF- odyssey of a kadet

[Bossgobbler]

Have you tried to mill 0.030 off the face of the firing pin retainer where the hammer hits? Also, try to reshape the firing pin so it does not hit on the edge of the rim of the case.

[joerchi69]

What weight hammer spring are you using, Joe?

In assembled condition 16,6 lbs and maximal operating 20,2 lbs. I was told by a spare parts seller in CZ country. So it is 20 lbs. plus an actual a spacer of 1,6mm = 0.629 inch to pre-load the hammerspring even more.

[joerchi69]

Have you tried to mill 0.030 off the face of the firing pin retainer where the hammer hits? Also, try to reshape the firing pin so it does not hit on the edge of the rim of the case.

No i haven´t worked on the firing pin retainer until now. Thank you - that thougth is new to me. I will give that a trial. What would be the benefit to remove 0.030 inch (0.7619 mm) ? A longer track to move the firing pin by the hammer ?

I will put the reshaping of the FP tip on my trail and error list. I also guess that with growing dirt (around from shot 150 on) the case is not reaching its end positon on the breech face. Because there the residue is pushed together shot by shot by the upcoming bullets. Hence the hit area of the tip is smaler, and, more significant closer to the stiff part of the rim. And the inition rate of the weak punch drops. The pistol is having missfires anyway, also with a cleaned gun with dust-free FP channel and tidy breech face area in the first shots. So the reshaping of the FP tip to have the best impact point on the weakest spot on in the rim area with the igniton compound.

How much coils do you have left on your FP spring ?

[painter]

WRT the reshaping...remove material on the opposite side that's already beveled. You want the strike about .010-.015 inside the edge of the case,. Keep in mind that all ammo has variances, so be conservative. The idea is to not waste energy on crushing the outside of the rim.

[joerchi69]

WRT the reshaping...remove material on the opposite side that's already beveled. You want the strike about .010-.015 inside the edge of the case,. Keep in mind that all ammo has variances, so be conservative. The idea is to not waste energy on crushing the outside of the rim.

Thanks a lot. I surely will try this modification to avoid the strong, just brass rim area without priming compound in it, to be striked by the FP. To have more momentum on the softer part of the rim. I will report it here when tested.

When interpreting centerfire anvil priming the ignition compound is crushed between the anvil and the brass to explode.
https://rws-munition.de/en/rws-hunting-area/about-us/research-and-development/the-primer.html
Transfering that to rimfire the ignition compound is crushed betwenn brass and brass. I´am not sure if the ignition compound really needs that sort of
"brass-anvil" to go off. But anyway the pics of the hitmarks i made are weak and to reinforce, compared to those imprints :
https://www.quora.com/How-do-rimfire-and-centerfire-rifles-differ

[painter]

Another item to check...make sure the roll pin that retains the barrel has not broken. That would allow the barrel to move forward when the case gets struck by the pin. If you want to get a replacement beforehand, the size is 3 x 12 mm.

Pay attention to the orientation of the split in the pin. It matters.

[adrian]

     Hiya and breaks my heart to have to see so many Kadet owners have to become machinists to make there .22LR go pop. Mine really only needed to have a 17pound main/hammer spring replace what ever was in there before and it went to less than 5percent light strike a range visit,using walmart federal ammo. Don't forget the smiths at cz-usa are avail if you call there during business hours. Be well.

[joerchi69]

WRT the reshaping...remove material on the opposite side that's already beveled. You want the strike about .010-.015 inside the edge of the case,. Keep in mind that all ammo has variances, so be conservative. The idea is to not waste energy on crushing the outside of the rim.

Did. Pic shows left FP hit area reshaped and smaler to the original on the right side. Will report as soon as used.
Will learn czech folk songs and orisons to intonate while shooting 

[joerchi69]

Another item to check...make sure the roll pin that retains the barrel has not broken. That would allow the barrel to move forward when the case gets struck by the pin. If you want to get a replacement beforehand, the size is 3 x 12 mm.

Pay attention to the orientation of the split in the pin. It matters.

Thank you. I´ve read that in some posts when fishing for ideas in the forum some weeks before. I checked it then and do frequent when cleaning.

[painter]

     Hiya and breaks my heart to have to see so many Kadet owners have to become machinists to make there .22LR go pop. Mine really only needed to have a 17pound main/hammer spring replace what ever was in there before and it went to less than 5percent light strike a range visit,using walmart federal ammo. Don't forget the smiths at cz-usa are avail if you call there during business hours. Be well.

It's somewhat puzzling why this kit is being so stubborn. Mine will run 100% with CCI SV, or Geco, for roughly 300 rounds and then need the feed ramp/breech face cleaned. All this with a 15 lb hammer spring.

[joerchi69]

WRT the reshaping...remove material on the opposite side that's already beveled. You want the strike about .010-.015 inside the edge of the case,. Keep in mind that all ammo has variances, so be conservative. The idea is to not waste energy on crushing the outside of the rim.

The original FP i had modified (input from the forum) to turn it 180 degrees but trying it out it for a short time showed a much worse ignition rate. But i believe it was just to much away from the rim or something else did not work. Maybe the FP was bent. Regret having no pics of the dents in the brass to show.


Because of your post i found that telling site:
You can clearly see if you are hitting way out on the rim, you are hitting folded brass, diminishing the power of the strike.
This is what target shooters do to their firing pins to get more reliable ignition:

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

[joerchi69]

Have you tried to mill 0.030 off the face of the firing pin retainer where the hammer hits? Also, try to reshape the firing pin so it does not hit on the edge of the rim of the case.

Do you mean to remove the material of the complete surface of the FP retaining plate ?
Or just the area where the hammer hits, and not in the slot-areas where the plate is hold in the slide ?

[painter]

WRT the reshaping...remove material on the opposite side that's already beveled. You want the strike about .010-.015 inside the edge of the case,. Keep in mind that all ammo has variances, so be conservative. The idea is to not waste energy on crushing the outside of the rim.

The original FP i had modified (input from the forum) to turn it 180 degrees but trying it out it for a short time showed a much worse ignition rate. But i believe it was just to much away from the rim or something else did not work. Maybe the FP was bent. Regret having no pics of the dents in the brass to show.


Because of your post i found that telling site:
You can clearly see if you are hitting way out on the rim, you are hitting folded brass, diminishing the power of the strike.
This is what target shooters do to their firing pins to get more reliable ignition:

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

Those pics will show you what you're looking for. Make sure you soften the edges whereever you file away material. You don't want to pierce the cases.

[joerchi69]

Softened the corners at the reshaped to smaler hit areas on the two modified FP`s and went testing today. That is the
new imprint (FP 2 on CCI sv) :



The hit area on the two modified FP´s could get shrinked down a little bit more and away from the strong rim ?

50 CCI sv and no ftfire, but two times the slide did not deliver a new round. One time he did also not stay open on the last round. Next pack 50 Blazers with one ftfire and on time slide not delivering the next round.
Changed to FP1 and finished a box of CCI sv with two ftfire and two slide delivering ammo errors.

Breech face after 150 rounds



I had checked the cleaned chamber at home. A live round just droped in by its weight. Now after 150 shots i checked it again and there was a certain hesitation to go in the last bit. Not much, but a little resistance on the last milimeters.. I cleaned the chamber and the breach face. The round went in without any drag.
Went on with the fourth box, 50 CCI sv again. One ftfire, missing two rounds in the chamber by slide (mag) failiure after the shot, one emty case was not extracted of the chamber and one stove pipe.
The next 50 Blazers went with just two ftfire in the black part of the target 25 meters away. Forgot to put on my shooting glases, and was positively surprised with a nice grouping with my regular glases 

Some conclusions:
The hit area on the two modified FP´s could get shrinked down a little bit more away from the rim ?
Because of the slide failures i assume the spacer under the hammer spring beeing to high. I will check the two modified FP`s just with the regular hammerspring and remove the spacer or thin it down a little bit more.
Extra power wolff gunsprings hammer springs are on the long way from the US to overseas.
I run a SA trigger. To put in the original DA trigger could be a thing to try.
A self made over all little bit longer and may be heavier FP is on my wish list.  Will see if i need to realise it.
To read up on how measuring the headspace an what are the right data could be a path to go too.

New hit marks on Blazer ammo



Most ftfires went on the second strike but that Blazer needed some arm (-ed) twisting

[joerchi69]

Checking the CZ for missing hammer striking power i was remembering a thread here where someone wrote to check the hammer on hitting the slide before the FP. He did not. But there was some repeatable irritation in the way of the hammer down. I pulled the hammer back on its rest means cocking position, held it with the thumb, pulled the trigger and holding it back. Then when lowering the hammer slowly down in the last fifth of the travel there was a little stoppage. Like he was going over something. First i found rubbing marks on the side of the hammer but it did not explain that click in and click out on the final move to the end position. It was the "disasembly rest" for the hammer wich locks somehow in and out on the "trigger related component who holds or loosens the hammer". = sear

Hammer cocked, toothpick on the (dont know the right expression) "disasembly rest" = half cock notch


Toothpicks on the lock up in and out parts, rattling on the hammer in the end of the movement to the FP