Strange looking primer strikes?

[stevemis]

Hi folks.

I've been noticing some funny looking primers while picking up brass after shooting. The primer strikes appear to have a protruding circular ridge around them. I'm not sure if these came out of one of my 9mm's (various CZ's) or if they were left by another shooter. I do know all but one of the cases appear to be new, and they have my headstamp. There is one case in the photo which was pretty old looking and isn't my headstamp (Speer).

I'm shooting factory new WWB.

Is this an overpressure telltale, or something entirely different? Perhaps it's normal and I've never noticed it before.

I'm not reloading yet... but I am picking up my brass.

Thanks!

Steve

 

[gaudio5]

in my time with reloading bubbled primer edges were over pressuer

 

[dmftoy1]

I can't honestly say I've ever seen anything like that . .but if that's overpressure I'd think that the gun shooting it must have alot of airspace around the firing pin. The only way I could see overpressure causing that would be if the primer was flowing back around the firing pin and on the pictures I've seen of that happening it didn't look ANYTHING like those pictures.

It'll be interesting to see what some others with more experience think.

If I was guessing I'd say that's not overpressure but it's purely guessing.

 

[jeepmor]

I've seen the 9mm do that before. 9mm runs at 30kpsi IIRC, that's pretty high. I've noticed a similar mark, rectangle, not circular, on 9mm brass before and suspect the same issue but just a different model of gun. The pressure is deforming the primer and pushing it back into the breech, where it extrudes just a little bit back into the firing pin hole.

I would not worry about it if these were out of a box of factory ammo. If it were out of a box of reloads, I might proceed more cautiously though, but I still wouldn't stop plinking if they only looked like that. As stated, I've seen lots of 9mm with this type if dimply mark on the primer.

As a reloader, I'd be real aware of how much effort is required to decap the primer. If it pops right out with little effort, I'd likely toss the brass. If they're still coming out like other brass from your 9mm factory loads, then I'd load away.

 

[Jim Watson]

Probably shot in a Beretta which has a chamfer around the firing pin hole so the incoming cartridge rim can't snag against a sharp edge. It gives the superficial appearance of a "cratered" primer from high pressure but is normal for the gun.

 

[stevemis]

Ok, next range session I'm going to bring a tarp (outdoor range) and see if I can figure out if it's one of my CZ's.

Thanks for the advice!

Steve

 

[JDGray]

My CZ dosn't do that, but a HK MP5 will Looks like the breech face is relieved arround the FP hole, for full auto action.

 

[strat81]

I've noticed a similar mark, rectangle, not circular, on 9mm brass before and suspect the same issue but just a different model of gun.

Probably a Glock. When I first got mine, it weirded me out. But every brand of ammo run through the gun does it. The breechface has a rectangular hole for the striker.

 

[The Bushmaster]

That indicates a firing pin that is a bit smaller then the firing pin hole or port. Or the hole is much larger then the firing pin... The primer is being forced into the port upon firing...As long as the primers are not rupturing I wouldn't worry about it too much. The only cure is a trip to the gunsmith...

 

[Steve C]

My primers look just like that when fired from my Taurus 92.

 

[stevemis]

Thanks for the pic. That looks just like the brass I'm picking up, so I'm going to assume everything is fine. Again, not 100% sure these are even coming from one of my pistols because there's always some cases people miss in the grass. I recently noticed it and if it is mine, I'd have to guess it's the latest addition to the stable, a CZ 75B.