Figure this one.

[chuck nelson]

So today I pierced a primer. After thousands and thousands of rounds down range, this is a first. This is definitely not a pressure issue. This is a 280 Rem shooting CCI 250’s, H4831, Nosler Brass and 140 partitions at 2950 FPS. Zip for any other indication of pressure. What bugs me is if you look at these primers, most look normal, one is slightly cratered, one looks like it should have pierced, and one did. Am I sending this thing off to be bushed?

 

[yomomma]

Check your pin first, you could have lost a bit of steel off the end

 

[chuck nelson]

I did. Pin looks good. The pierced one was round one.

 

[supernova]

Those primers are nice and round, caseheads are clean and sharp. Definitely not a pressure issue. I would have to geuss you have a bad batch of primers. The strikes are rather inconsistent. Some are clean and sharp, others cratered and then obviously the pierced. Edges look about the same on all so I'm wondering if wall thickness varies amongst them?

 

[chuck nelson]

Those primers are nice and round, caseheads are clean and sharp. Definitely not a pressure issue. I would have to geuss you have a bad batch of primers. The strikes are rather inconsistent. Some are clean and sharp, others cratered and then obviously the pierced. Edges look about the same on all so I'm wondering if wall thickness varies amongst them?

I’m wondering the same. They are a new lot of primers.

 

[Ganderite]

Pistol primers?

Weigh some rifle primers and some pistol primers and compare to the problem box.

 

[chuck nelson]

New lot is a tenth heavier.

 

[BigUglyMan]

It's a one off. I wouldn't worry about it. If it started being a regular thing then I'd be concerned.

 

[stubblejumper]

The firing pin is certainly off center.

 

[chuck nelson]

Which is not the issue.

 

[bigedp51]

If the case shoulders are bumped back too far you can have excessive head clearance or air space between the bolt face and the rear of the case. The firing pin hits the primer and the cartridge goes bang, then the building chamber builds up pushing the primer out of the primer pocket. When the primer backs out of the primer pocket it flows back over the firing pin. This action of the primer backing out over the firing pin acts like a cookie cutter and punches the center out of the primer.

It could also be bad primes that are soft or excessive clearance around the firing pin and the bolt face. Remove the primes and look at them closely and see if they are mushroomed and bulging below the rounded edge, This would be another indication the primer backed out excessively and expanded around the base.

Below from the Sierra reloading manual.

Below CCi 400 rifle primers fired in a AR15 but they have a thin .020 primer cup and the same thickness as pistol primers.

The cause of this was bumping the shoulder back too far and excessive head clearance. This allowed the primer to back out of the primer pocket too far and the firing pin punched the canter out of the primer.

 

[chuck nelson]

I’ve checked that already unfortunately. This is new brass with between 1 and 2 thousandths head space. So that shouldn’t be the issue.
I have a friend that mentioned the weak spring issue and I’m going to try that.

 

[bigedp51]

When you say "new brass" I have never seen a brand new unfired case with only .001 to .002 head clearance. The last Winchester .243 cases I bought were .009 shorter than my GO gauge so I'm guessing the head clearance was .011.

If these were the second time the cases were fired then I would agree about your .001 to .002 headspace or head clearance.

Do you have a Hornady cartridge case headspace type gauge or any type gauge that measures from the datum point on the shoulder.

I would also try another brand of primer with cases fire formed to your chamber, meaning minimum shoulder bump/head clearance.

Below my Remington 700 bolt face looks like below with a beveled firing pin hole. All my primers flow into the beveled area and the only fix is the have the bolt bushed.

 

[chuck nelson]

New

Fired

 

[chuck nelson]

Now you’ve seen it twice (different rifle).

New

Fired

 

[bigedp51]

Are all your photos above of Nosler brass?

Do you have a custom chamber or is all Nosler brass this close to perfect.

I have a box of unopened Nosler .223 brass, I guess its time to open the box and compare them to headspace gauges.

P.S. Thanks for making me feel bad and teaching me something new.

 

[chuck nelson]

Laughing. The top is Nosler brass and custom chamber, the bottom is Lapua brass and a custom chamber.

Domestic brass will probably not be as good, nor will a factory chamber.

 

[titch--]

Could it be primer seating depth? From the picture they all look good. :/

 

[Duck_Hunter]

I’d bet on a bad batch of primers. I had the same experience with some Winchester small rifle primers once.