Bulging primers

[Wild Deuce]

What gives? I looked at my brass following a day at the range and noticed something peculiar. The primer strikes on my Federal ammunition were "innies" whereas the strikes on my Remington UMC ammunition were almost "outies." Some of them even resembled a cone volcano. Two or three even visibly bulged past the cartridge base. I inspected the other unfired rounds from the same box and they seem normal. I don't reload yet but I'm already reading up on it and started saving brass. Is there anything I am missing here?

This is all factory new ammo and I plan on using the spent brass for when I start reloading.

Information:
Federal Premium HST 9mm 124 grain
Remington UMC 9mm 124

Springfield Armory EMP

Images:

 

[Steve C]

It isn't uncommon to see lower pressure ammo have some primer budging or flow like you're picture shows.

Nothing to be concerned about.

 

[Wild Deuce]

Thanks, Steve C. I was wondering if it was a quality control issue since the Federal ammo is premium defensive ammo. I thought the Remington UMC ammo might just have lower quality primers since it's just range ammunition. I imagine there are variations in pressure even if they are both rated standard and not +P?

 

[The Bushmaster]

I, also, see no problem...

 

[Walkalong]

Yep, no problem, but it doesn't speak well for the quality of the ammo.

 

[W.E.G.]

That is most likely not an over-pressure issue, as the circumference of the bulged primers is still nicely radiused.

That is most likely not a gun issue, as the other "known good" ammo shows no such features.

I believe it is soft and/or thin primer cups on that batch of ammo.

Keep an eye on that ammo. If the cup actually ruptures, the escaping gas will erode your firing pin, the firing pin channel, and the boltface of your weapon.