Primer cratering.. SOLVED THANKS FOLKS!

[243winxb]

Why would this happen randomly

The firing pin channel may get worn from spring contact. On firing , the spring may drag or make contact with the worn groove. This slows pin velocity or may even cause misfires. Seen this in a 22lr . Should not apply to a good custom action?

A weak spring may get pushed back by the high pressure. Pin not in contact with primer long enough. Revolvers have hammer bounce on firing.

ckaberna, Never shot Berger 108 before.

Try lowering the powder charge. The new bullet may have a thicker jacket and longer bearing surface, raising pressure.

That last photo is a great one. Seen it before online in 223, but not that bad. High pressure was the cause.

 

[ckaberna]

Believe it or not...it's a fact. It's not just a BAT thing. How old is your BAT? They changed the spring and pin diameter after 2014 I think. Went from .240 to .280. If you have the .240 pin/spring....I'd recommend upgrading to the heavier .280 pin and spring.

Please don’t take my comment as not believing this. I just don’t know enough to understand the physics behind it.

 

[LRPV]

Firing pin hits, bounces off back into the bolt, primer flows into pin hole, firing pin bounces back out and contacts the primer again leaving that nice little tit you see. If your pin spring is strong and/or pin heavy enough it will hit the primer and stay put. This is how it was explained to me.

 

[CaptainMal]

Strange this should come up now. Yesterday I shot one of my BRA's in a paper 600 yard match at Manatee. Couple days earlier I changed firing springs in that Stolle Kodiak action from a Tubbs Duo-spring to a new 28# heavier Wolf spring. About one in five cases showed a little bit of your "proud" primer situation. Now not as severe as yours but still there. Never had that with the load before using the old spring.

My idea is now I will drop the load .1 -.2 of a grain and see if that corrects the issue. My assumption was the stronger firing pin spring was making a change in the CCI 450's ignition pattern and creating a bit more pressure. That's near the opposite of the help ideas others gave you. I have no clue what is right but I sure would look at pressure issues with the set-up you have.

 

[ridgeway]

Please don’t take my comment as not believing this. I just don’t know enough to understand the physics behind it.

There is many others out there that don't believe it or in denial that it's not possible. They end up chasing their tail and end up shooting a lower node thinking that it's pressure/load causing the createring. It's not always the fire control system causing it, but highly possible. It's up to the shooter to evaluate and go through a process of elimination to remedy the problem.

 

[ckaberna]

Firing pin hits, bounces off back into the bolt, primer flows into pin hole, firing pin bounces back out and contacts the primer again leaving that nice little tit you see. If your pin spring is strong and/or pin heavy enough it will hit the primer and stay put. This is how it was explained to me.

Thanks for explaining.

 

[Texas10]

If you calculate the force on the firing pin, based upon what is probably 60,000 psi chamber pressure, you'd be amazed at how much force is being exerted on the primer cup and firing pin as it flows back into the bolt head. I have some primers that look exactly like yours. I disassembled them and looked at the back side with 20X and could see how the metal moved while looking at the high pressure side. Very educational!

I my experience, it's definitely a spring vs pressure issue. Change one or the other to eliminate the problem.

 

[Gilbert Garza]

I had this issue on my AI, I had a large firing pin

I had enough pressure to overcome the spring and have the cup flow back into the hole occasionally piercing. I bushed the bolt body to a small pin and eliminated this issue as it was harder for metal to flow through a smaller hole.

Measure the slop between firing pin & hole.

 

[johara1]

There is little more to it than going to a .280 firing pin and spring. You will need the new shroud for the .280 pin or ream the hole to fit the .280 firing pin in the old one..... jim

 

[ckaberna]

There is little more to it than going to a .280 firing pin and spring. You will need the new shroud for the .280 pin or ream the hole to fit the .280 firing pin in the old one..... jim

Thanks for that advice. I need to pull mine apart and see what I do have. Is their an advantage to changing to larger bodied pin? I understand inertia but I don’t seem to have that problem. My issue is keeping the pin down on primer. I see bat has heavy and light springs for both, not sure which is better, I assume the heavy for heavier loads?

 

[johara1]

Thanks for that advice. I need to pull mine apart and see what I do have. Is their an advantage to changing to larger bodied pin? I understand inertia but I don’t seem to have that problem. My issue is keeping the pin down on primer. I see bat has heavy and light springs for both, not sure which is better, I assume the heavy for heavier loads?

Never assume nothing, A few smiths made a fix for the light firing pins. A weight and shorter spring due to the weight that helped with ignition, most that needed it were the shorter than the B. The firing pins were adjustable then, now it is not the case, 22-24 pound at the.120 to .130 pin fall height seems to work for me..... jim

 

[243winxb]

https://www.batmachine.com/faqs/ See

Instructions:
How to remove firing pin assembly from bolt..

I dont see any thing about light or heavy spring. Contact them maybe?

After reading all of that, i would lower the powder charge or change powder, first?

You need help from someone shooting the same rig. Not i.

 

[johara1]

look at the online store, for firing pin springs.... BTW. that is a very old video ...... jim

 

[JMayo]

Id question powder charge if it's never happened before.
That second one is tripping me out ! I've never seen anything like that.

 

[ckaberna]

Me either and I want to believe powder charge but it’s so random. Last three shots at the highest load all primers were perfect?
Called bat and they are perplexed as well. I have two new springs on the way. One heavy and one light. Been measuring brass and apparently I set it back .004”instead of the .001. I had not set calipers correctly and actually made a note of it in my log. With the 40degree shoulders in this I am not sure if that would this effect or not?? So I have got two things to try the springs but I also want to jam the bullets in the remaining “short” cases to get them back right.

 

[JMayo]

Me either and I want to believe powder charge but it’s so random. Last three shots at the highest load all primers were perfect?
Called bat and they are perplexed as well. I have two new springs on the way. One heavy and one light. Been measuring brass and apparently I set it back .004”instead of the .001. I had not set calipers correctly and actually made a note of it in my log. With the 40degree shoulders in this I am not sure if that would this effect or not?? So I have got two things to try the springs but I also want to jam the bullets in the remaining “short” cases to get them back right.

I use the ones I set back too far for sighters. (Bench rest) I use a pma tool on my die to creep up on setback. The thickness of the rim can be a factor.
Maybe the double tap of the pin did it, idk.
I ff using 400 primers didn't jam any extra. None did that.
I wouldn't think my pin spring on a bat action after 1500 rounds needs anything.

 

[ckaberna]

I use the ones I set back too far for sighters. (Bench rest) I use a pma tool on my die to creep up on setback. The thickness of the rim can be a factor.
Maybe the double tap of the pin did it, idk.
I ff using 400 primers didn't jam any extra. None did that.
I wouldn't think my pin spring on a bat action after 1500 rounds needs anything.

What would cause a “double tap” Besides a weak spring.

 

[ckaberna]

May have just discovered the problem as it relates to the randomness of my issue. I was told this barrel was a no turn well apparently a .272 is NOT a no turn for my lapua brass. Some brass measurements are .0143 wall while some are right at .0132. Matter of fact the ones with the issues are the thick ones. How STUPID of me. I will learn, maybe this post will help somebody else at some point. Thanks for all your input and feedback maybe one day I can return the favor!
Kevin

 

[JMayo]

May have just discovered the problem as it relates to the randomness of my issue. I was told this barrel was a no turn well apparently a .272 is NOT a no turn for my lapua brass. Some brass measurements are .0143 wall while some are right at .0132. Matter of fact the ones with the issues are the thick ones. How STUPID of me. I will learn, maybe this post will help somebody else at some point. Thanks for all your input and feedback maybe one day I can return the favor!
Kevin

A 6mm ? 272 is a no turn. Way bigger than a loaded round. .268 loaded round.
A kinda "double hit" with case not fitting as in fire forming,comes from the initial pin to primer strike, case goes forward, firing happens, case comes back into pin.

 

[ckaberna]

A 6mm ? 272 is a no turn. Way bigger than a loaded round. .268 loaded round.
A kinda "double hit" with case not fitting as in fire forming,comes from the initial pin to primer strike, case goes forward, firing happens, case comes back into pin.

If you have bought brass lately you may want to measure them. Before shooting.