AR 15 barrel caliber identification help. (update)

[Daddymac]

Sooooo, what? Blown primers are virtually always pressure, not headspace. Pierced primers, seldom due to pressure but pressure is a contributing factor. So, what did you have and what are you saying?

Primer is gone, missing, de-capped, but only in one case out of 30. I assumed it was a pressure issue, in my reading on the subject "they" claim that 5.56 "can" pressure spike in a .223 chamber because of the shorter leade in the .223, but according to the info I have seen this is related to a bullet profile issue. The bullets in this ammo was standard fair 55gn. FMJ factory ammo and they were all the same.

I just quickly looked over all of the cases, 25 looked fine, 5 looked suspect to me. One has a missing primer, two have what looks like leaking around the primer, and all five have ejector impressions, again the others looked fine. I have had this ammo for a while and I do not know the absolute origin, I think it was a gun show no name brand probably made overseas ammo, so maybe the ammo is to blame?

I have flattened out a few primers in my day, but have never had one completely missing so it spooked me a little, especially with the primers being crimped. I'm going to look deeper into the cases, check the rifle out along with a good cleaning and run a few .223 through it to see what happens.

Thanks for the help.

 

[gunsandgunsmithing]

Primer is gone, missing, de-capped, but only in one case out of 30. I assumed it was a pressure issue, in my reading on the subject "they" claim that 5.56 "can" pressure spike in a .223 chamber because of the shorter leade in the .223, but according to the info I have seen this is related to a bullet profile issue. The bullets in this ammo was standard fair 55gn. FMJ factory ammo and they were all the same.

I just quickly looked over all of the cases, 25 looked fine, 5 looked suspect to me. One has a missing primer, two have what looks like leaking around the primer, and all five have ejector impressions, again the others looked fine. I have had this ammo for a while and I do not know the absolute origin, I think it was a gun show no name brand probably made overseas ammo, so maybe the ammo is to blame?

I have flattened out a few primers in my day, but have never had one completely missing so it spooked me a little, especially with the primers being crimped. I'm going to look deeper into the cases, check the rifle out along with a good cleaning and run a few .223 through it to see what happens.

Thanks for the help.

That's a pretty crazy a rare difference but a good example for why they say to only fire the correct ammo in any gun. Lots of remaining possible causes though

 

[Daddymac]

Did a little digging this AM, found that the ammo is a headstamp CJ 92 batch of Norinco, (Chinese mfg.) yellow box with red print and I did get it at a gun show, looking through comments on some other sites it seems to have a reputation for being a little on the hot side, saw some pics with blown primers like the one that happened to me.

I feel a little better but still going to cautiously run some LC 5.56 and some .223 a little later, I will update.