Pierced primers

[Jcp73]

I was shooting my Grendel today and had 4 out of 8 primers pierced. I did look at the first 2 cases they were fine. I didn't notice the problem til I picked up. I've shot these before, and had no problem. Could this just be a bad firing pin? These are reloads cci primer 129 sst 26.5 varget horn case thanks

[txgunner00]

Could be a number of things but the firing pin is the first thing I would check for dings or chips. Really need more info on the rifle & load help any further.

[LRRPF52]

Guys that have tried Varget usually say that it isn't ideal for the Grendel. I haven't used it, but I remember discussions about it on the old Forum.

[Jcp73]

Could it be the powder? I've shot these before. I've got some blc2 ican try. The weird thing is why all of a sudden?

[davidj]

The only pierced primers I have had were on factory 123gr A-Max. A total of three; all from different lots over several months.

[PA_Allen]

Which cci primer were you using? The 400s have a thinner cup than the 450s and BR4. I had 5.56 service rifle loads that pierced primers with the CCI 400s but were fine with the 450 or rem 7.5 primers with thicker cups. Also too large of a firing pin hole in the bolt face can lead to pierced primers.
Best,
PA

[Jcp73]

I shot 3 factory hornady today. 1 of 3 pierced. When I look at Fp it looks like the pin is chipped. I'm getting older so it's hard to see that small. I also noticed that the cases that werent pierced had indents ,so they almost pierced . It has to be the pin. How common is that? Thanks

[Jcp73]

I put the new Fp in and shot 3 hornady 3 hand loads (129 sst 27gn blc2). 1 of the hornady might be pierced or it's real deep. That has slight ejector marks. 2 of them have slight bit of cratering. The hand loads look fine. Non of the primers I would call flattened. The one thing I thought about was this all started after changing the lower.maybe the carrier to I don't remember. I had this thing running good On a carbine stock/buffer. Then i put it on a rifle lower . Im also now using a ar carrier and Not the M16 carrier i think i was using. Could that be my problem? I can start swapping parts ? Any suggestions? Thanks

[LRRPF52]

Put the carrier back in that was working, but your bolt is what controls firing pin protrusion depth. Check that load to see if it is under max. What chamber do you have?

[Jcp73]

My handload I think a starting load from hornady. My barrel is from midway says 6.5 Grendel bolt is also from midway.

[Jcp73]

Also are the hornady factory loads hot? Just wondering

[LRRPF52]

I don't see any signs of hot loading in the Hornady 123gr AMAX I just burnt this past week, from lot # 3110573. It's a great load out of my 16" AA Grendel barrel/bolt.

If you can measure the neck diameters of your spent cases, that will tell us more about your chamber. There were issues where different companies were marking their barrels as "Grendel", when they were some variant chamber. A variant chamber with a short leade will generate higher pressures with certain projectiles loaded to COL's that would otherwise be fine in a SAAMI Grendel chamber, we just don't know who or to what chamber dimensions many of these variations were cut to.

We are seeing more and more of this with non-Grendel chambers, where accuracy is not there either. This is why Bill A. was adamant about barrel-makers following the chamber dimensions to a "T", as well as some other Quality Control standards that ensure the customer gets a great barrel that will actually run ammo through it safely.

I have pushed the pressures with several of my load development strings, and never even come close to anything like piercing primers.

[Lead Chucker]

I got my barrel from satern in April 2011, it has a short leade, I have to load my rounds with a shorter OAL than what is listed. But I have never had any problems with pressure or accuracy. Never had pierced primers.

[Jcp73]

The necks are .298 what is a "true" Grendel .300? This might be more of a bolt being out of spec? I don't see this being a safety issue do you? Thanks

[LRRPF52]

Piercing primers is a potential safety issue, much more so than cratered primers or ejector flow. Something wrong is going on when you are piercing primers. .298" fired neck diamter sounds like you have .300" neck chamber.

If the firing pin hole in your bolt is too larger, you could get pierced primers. Disassemble your bolt and see if ther residual metal is wrapped around the firing pin. That is a dangerous situation in itself.