will a weak firing pin spring cause accuracy issues?

[bigngreen]

Firing pin spring can absolutely make a difference in the quality of ignition, you see it regularly in bench rest rifles, sometimes it's the act of replacing the spring that makes it better also, cleaning it up and things find home a little better so you get a better strike.

 

[vegas steve]

mr green i believe you are really on to something.the change in my rifle reflects this concept to a t

 

[vegas steve]

the trigger even breaks cleaner and crisper than before too

 

[vegas steve]

Did some testing today at 200 yrds.the weak spring wd always give me groups that averaged around.650-.750 with an occasional flier.the new spring took care of the fliers but didnt really tighten the groups.the big difference was the fps.the pet load was always around 2900 to 2915 before.same load in even colder weather now zips at 2996-3011 fps,indicating a harder hit does in fact make for a better burn

 

[243winxb]

Or did the firing pin strike set the shoulder back a few thou, reducing case capacity.

 

[vegas steve]

the firing pin wd have to be the same diameter as the case,and hit with 250+ft lbs of force to bump the shoulder.

 

[gohring3006]

Even if it was possible to set the shoulder back with the firing pin.
The case would expand back to chamber specs, and would be equivalent to full length sizing and not raise velocity...
Man those would be some hard primers to allow the case to crush at the shoulder.

 

[Greyfox]

It's possible that a weak, or broken spring spring, resulting weak primer impact could effect the ignition consistencies of the priimer, particularly given that there are differences in primer cup thickness between the brands. I once installed a light hammer spring in a S&W revolver, causing occasional duds and hang fires. I was checking increased spring strength with primed-only cases. There was definitely a difference in the "pop" created between the light spring and stronger hammer springs. I think the louder pop could be indicative of a faster/hotter burn, that could effect velocity.

 

[243winxb]

Even if it was possible to set the shoulder back with the firing pin.
The case would expand back to chamber specs, and would be equivalent to full length sizing and not raise velocity...
Man those would be some hard primers to allow the case to crush at the shoulder.

The 223 shoulder in a Savage Axis can be set back .006" from the firing pin strike.

Military tests show a 4% difference in case volume between new brass and fired brass. 5.56

I found the set back by accident. Defective primer.

Have not checked 243 or 06. Old and lazy.

My brass was not annealed, but if it was softer, would set back be more?

 

[vegas steve]

i wd figure any time the powder was ignited, the pressure wd swell the case against the chamber walls.ive never heard of a case getting bumped shorter at the shoulder from being fired.brass wd last forever if that happened

 

[243winxb]

Head to datum measurement changing VS case volume

Yes, on firing the case expands, moving the shoulder forward.

When the defective primer did not fire the round, i took measurements before pulling the bullet. Then more testing showed a 2nd pin strike moved the shoulder back more.

I then made 3 empty cases , used primers, with known head to datum measurement. The firing pin strike set the shoulder back on all 3.

The Savage lets the case move forward from the pin strike, till the extractor stops it.

This may not happen with a Remington 700 type extractor? And may not have an effect on larger cartridges?

To old and lazy to test my Remington 40X or other riflles.

 

[vegas steve]

Sounds like that savage has excessive headspace