Punctured primers

[1950Plymouth]

1957 S prefix gun here. Ive replaced all the springs and swapped many other parts (extractor, disconnector, trigger, bull creek arms muzzle brake etc) in my efforts to tune it. I verified the bolt goes into battery and locks properly and the disconnector does its job, disconnecting once the bolt leaves battery.

 

I had noticed when i first fired the gun a few months ago after my paperwork cleared, that it strikes primers a bit off center. Even if i swap firing pins. I didnt think much of it because i had to focus on extractor issues. Finally, thats mostly sorted out.

 

I put in a brand new Keystone firing pin. It broke the tip on the first magazine and left a jagged dagger of a tip. It continued to fire, albeit poorly. I stopped as soon as i realized what was wrong.

 

I put in a ken christie pin. The gun fires ok on full auto, some jams, but i picked up my brass and 75% of them (speer 230 grain ball) had punctured primers straight through. Daylight. I took the gun down and found the pin, spring and channel all loaded with carbon from where the gas was dumping. Sigh.

 

I had shortened an original pin to do the inertial firing pin mod, i had not tried it yet. So i put it in also hoping it would reduce striking energy. It does. This works best so far. Most primers look properly struck. But im still getting a 5 to 10 % primer punch through rate. This is not normal. Ill try different ammo next time?

 

The gun sometimes hesitates or stops firing during full auto. I think the issues must be related. A gas leak out the primer, reducing pressure must slow the action down or short stroke it.

 

I will try a stronger FP spring. This one now has a collapsed coil on the bolt face end. I am pretty careful and i dont remember it being that way when i installed it. I wonder if the heat from gas escaping the primers caused it to lose temper. All the more reason to replace it.

 

The experiment continues . Fussy gun. But fun when it is in a good mood. Ill get there eventually.

Edited October 6, 2022 by 1950Plymouth