How to recognize overpressure from primers

[Turo]

I'm trying to figure out if these casings look like the pressure was too high. These were loaded to the maximum (gradually worked up to) charge of Longshot with a 180gr bullet:



For comparison, this was a much lower powered load, only a half grain above minimum recommended:


A couple more comparisons, this is an unfired primer:


And this is a factory round:


I'm not 100% sure what to look for with regards to overpressure, but all these rounds fired fine, cycled perfectly through the Glock, and were all fairly accurate.

[M27]

I would say. No. Higher than the other but not over.

On an hot load the outside rim of the primer, in the little crevice between the primer and brass, will be pushed flat. Closing the gap.

[huckberry668]

High pressure signs are hard to tell from handgun brass to be honest. Especially from the small primer of a 40sw. They look to have the breech face imprinted on the primer cup. Are there any signs of 'Glock Bulges' on any of the brass?

I'd be very uncomfortable with 'reloading' for Glock at max loads.

[huckberry668]

I would say. No. Higher than the other but not over.

On an hot load the outside rim of the primer, in the little crevice between the primer and brass, will be pushed flat. Closing the gap.

For a rifle round that'd be the case but pistol rounds are hard to tell. It'd blow up before the primer flattens out like they do on rifles. I wouldn't use that to test a 'less supported' Glock chamber.

[M27]

And glocks are +p+ so if you like how the rounds shoot than use them.

[M27]

For a rifle round that'd be the case but pistol rounds are hard to tell. It'd blow up before the primer flattens out like they do on rifles. I wouldn't use that to test a 'less supported' Glock chamber.

I would argue and take pics of my 44mag and 45acp to prove you wrong. But because the 40 is small primer you may be right.

[rsrocket1]

Excessive pressure on primers are usually seen when the primer is flattened around the edges or when it flows so that there is no gap between the primer and the primer pocket. That said, with soft primers (particularly brass colored Federal primers), there will be flattening even at normal pressures so you can't rely on primers all the time to indicate excessive pressure.

Your fired rounds do not look excessive in pressure, but as the others said, I would not load to max for a Glock.

[gun fu]

You are looking for "primer flow" High pressure load with strike breechface so hard so that the primer "flows" back in firing pin hole, potentially obstructing the the FP hole.

Another indication, as M27 said, no more "curve" to the cup, more of a flattened look.

If uncomfortable with it try diff primer/powder combination.

Glock bulges are common with the factory barrels since the chamber is a bit on the "loose" side. Which is cool, I would just use the full length case resizer like Lee's Bulge buster.

IMO, looking good to me...

DVC

[Turo]

I guess I forgot to mention that these are CCI small pistol primers. I'm not sure where they fall on the hard---soft gradient.

It sounds like most everybody agrees that these aren't too high. That's reassuring to hear.
The max loads were really just a test, I only loaded 5 and shot them through the chrony. 1100fps 180gr bullet out of a 3.5" barrel seemed fairly impressive and I wanted to make absolutely sure the pressure wasn't too high. The load is within the "safe" loads listed by Hodgdon so I wasn't terribly worried, but one can't be too careful reloading.

[Turo]

High pressure signs are hard to tell from handgun brass to be honest. Especially from the small primer of a 40sw. They look to have the breech face imprinted on the primer cup. Are there any signs of 'Glock Bulges' on any of the brass?

I'd be very uncomfortable with 'reloading' for Glock at max loads.

The "Glock bulges" on these rounds are far less pronounced when compared to even really low powered factory loads. For example, factory Federal 180gr, when fired through this gun show quite a bit of bulge, and compared to my handloads they look pretty ridiculously large.

So, yes, the bulge is there, but is relatively small.

[bruceflinch]

I've never seen a Glock firing pin mark quite so pronounced before!

[r3dn3ck]

^^ I have, factory ammo all the time. Especially 9mm, rarely .45acp.

none of those appear to be over though a few were looking to be up near the top of normal working pressures. A chronograph is your next purchase as at this point you're loading blind. I never get glock bulge on my rounds but I do not shoot .40 S&W which was the only real offender I've ever seen. I wouldn't load any hotter and really if you're target loading, I'd drop half a grain of charge weight.

[Bill Steele]

Those primers look fine, but as others have said, the hardness of the primer cup material (CCI are relatively hard) and the size of the primer (large primers tend to flatten easier than small primers) also have a bearing on when you have entered the twilight zone. Primer flattening is only one measure.

I frequently load to max with my Glocks. Before I get to that point with any combination of powder and bullet, I work up every load watching for signs of pressure and especially watching for how large the bulge gets where case is unsupported. Timing can also effect this bulge and the appearance of the dreaded smiley.

The reason you have to work each load up is each powder bullet combo is different. Some powders will barely bulge your brass at all at max (their book max), some powders will wreck your brass (a smiley, or in my case if I have to use a separate push through die step, I toss that brass).

As r3dn3ck points out, a chrony is a great investment in this hobby and I agree with regard to loads, best accuaracy is rarely achieved at max loads.

Good luck, have fun.

[Turo]

I didn't realize others had replied to my thread until just now!

I've never seen a Glock firing pin mark quite so pronounced before!

It may be my gun, because I've seen this on almost every round I've ever shot through it. Factory rounds are the worst (not that this is bad but they do it the most).

^^ I have, factory ammo all the time. Especially 9mm, rarely .45acp.

none of those appear to be over though a few were looking to be up near the top of normal working pressures. A chronograph is your next purchase as at this point you're loading blind. I never get glock bulge on my rounds but I do not shoot .40 S&W which was the only real offender I've ever seen. I wouldn't load any hotter and really if you're target loading, I'd drop half a grain of charge weight.

Even though you're banned, I'll still respond in case anybody else wants to know. I just recently got a Chrony, and have been shooting these loads through it. I think I mentioned it earlier in the thread, but these 8.0gr Longshot max recommended loads were pushing 1100fps out of my 3.5" barrel, whereas the lighter loaded example was 7.1gr and it was averaging 1000fps, 180gr bullet.

Those primers look fine, but as others have said, the hardness of the primer cup material (CCI are relatively hard) and the size of the primer (large primers tend to flatten easier than small primers) also have a bearing on when you have entered the twilight zone. Primer flattening is only one measure.

I frequently load to max with my Glocks. Before I get to that point with any combination of powder and bullet, I work up every load watching for signs of pressure and especially watching for how large the bulge gets where case is unsupported. Timing can also effect this bulge and the appearance of the dreaded smiley.

The reason you have to work each load up is each powder bullet combo is different. Some powders will barely bulge your brass at all at max (their book max), some powders will wreck your brass (a smiley, or in my case if I have to use a separate push through die step, I toss that brass).

As r3dn3ck points out, a chrony is a great investment in this hobby and I agree with regard to loads, best accuaracy is rarely achieved at max loads.

Good luck, have fun.

Thanks for that bit of info there. As for the bulge, I've seen much worse than these with factory ammo in this gun, but I've never seen much of a bulge. It's a later model gen 3, which I understand has had a slight fix of the "unsupported chamber" issue common with earlier models. I even compared how much of the case was unsupported against my buddy's Beretta 92fs in 9mm, and I couldn't tell a difference.

I think my next step is figuring out accuracy since I rarely benchrest my pistols. I have a hard time judging accuracy differences with such a short sight radius.

Thanks for the input guys, it helps!