light strikes FTF- odyssey of a kadet

[joerchi69]

All the CCI SV I have looks similar to the box on the right. Instead of saying 35EU, it says 0035. I wonder if they make it differently for Europe?

The new design is new to me too. (I think it is the same ammo inside). I used the old and new packed boxes alternating the last two range sessions.

Your last set of results are approximately what I get, but I can use a lighter hammer spring and an unmodified recoil spring. I do have a lighter firing pin spring that I got when CGW had them available. The only other thing I can suggest is to try a weaker firing pin spring, not shorter, weaker. Some have used the spring from a ball point pen.

I will give ball point pen springs a try, replacing the shortened FP spring !

[joerchi69]

Due to getting another box from the czech republik with new firing pins made in USA i have new spare ones now. So i additional narrowed the flanks of my FP3 a little to maybe have more impact "force" on the priming compound and to see what happens.

Left to right, modified firing pin tips, FP1 - FP3.  FP4 new original size.


New FP4 from
https://www.cz-spare.parts/firing-pin-cz-75-kadet-usa-no-54

[joerchi69]

Left to right, modified firing pins, FP1 - FP3.  FP4 in new original.

[joerchi69]

Tested the FP3 with the reduced hit area on the flanks. And compared the shortened FP spring to the use of a ball pen spring. Cut down Kadet recoil spring, minus 6 or 7 coils.  Original 20 lb hammer spring in the grip. Alternating new and old design paper boxes of CCI SV.
On the first box (new design) i had 1 light strike, 1 time the slide stayed not open on the last round, 1 missing round in the chamber wich was not stripped from the magazin.
Second box (old design) one light strike. Cleaned the contact areas barrel face and slide, rim, ramp and chamber then.
Third box (new d.) i changed to the ball pen spring. No issues.
Fourth box (old d.) one time slide closing on the last round of the mag. Cleaned the contact areas barrel face and slide, rim, ramp and chamber then.
Fifth box (new d.). I put in the new unmod. FP 4 and kept the ball pen spring. No issues.
Sixth box (old d.) one light strike and one missing round on the last 3 shots.

Looks like the ball pen spring reduces light strikes compared to the shortened FP spring. Will go on with it and FP3.

[joerchi69]

First row   FP3, shortened FP spring
Secnd row FP3, ball pen spring
Third row   FP4, ball pen spring

[painter]

Try a lighter hammer spring now. That should eliminate the slide closing on the last round.

What happened to the FP that had the strike off the outside edge of the rim?

[joerchi69]

Try a lighter hammer spring now. That should eliminate the slide closing on the last round.

What happened to the FP that had the strike off the outside edge of the rim?

It is FP3. But somehow the rim of the case is now hit too ? Or it just looks like so due to optical adverse conditions.
Before (top) and after (down) shaping the flanks of FP3.

[joerchi69]

Left to right:
Firing pin original, FP spring original length, shortened FP spring (in use) , ball pen spring (in use now)

[painter]

Try a lighter hammer spring now. That should eliminate the slide closing on the last round.

What happened to the FP that had the strike off the outside edge of the rim?

It is FP3. But somehow the rim of the case is now hit too ? Or it just looks like so due to optical adverse conditions.
Before (top) and after (down) shaping the flanks of FP3.

I'd take a bit more off that pin to get the entire strike on the flat part of the case

[joerchi69]

I'd take a bit more off that pin to get the entire strike on the flat part of the case

Did this to FP two some time ago, but the ignition rate got worser. In the moment i  just go with the idea to smaller the chissel style FP at the flanks. To get the little bit stronger hit and also at the bevelled area of the brass. Somehow i got the impression the rimfire works better with hitting this area. Maybe to have the priming compound sqeezed between brass and brass in the smallest compound volume area inside the rim. To have the hammer-anvil effect there between brass and brass.

[joerchi69]

FP dents from 1-4, original 20 lb hammer spring, ball pen spring with the firing pin



same motive, different light and zoom

[painter]

Pin #2 is definitely too small of a print.

#3 is very close. I'd take a little more. When I profiled my pin I was trying for 1 1/2 times case thickness from the edge.

This is Eley...the brass seems very soft.



and some CCI before, and surplus S&B after...

[joerchi69]

Hello Painter,
how many lb is the hammer spring used for these dents ?
Do you have missfires ?
What FP spring is used ? Original, shortened, ball pen ?
Greets,
J

[painter]

The CCI and S&B marks were made with a 17lb spring. The Eley cases were fired in a CZ rifle.

I have occasional misfires. I had two or three light hits today in 70 rounds. They both went bang on the second hit. It always means it's time to clean There are about 230 rounds since the last cleaning.

The firing pin spring is a CGW spring that isn't available any longer. I'll take a picture of it the next time I clean the gun, which will be soon. I also run a CGW Race hammer, which is heavier than a stock hammer.

Pretty much everything I've done is in this thread... https://czfirearms.us/index.php?topic=86684.msg649425#msg649425

[painter]

Picture of FP and spring...