Pressure indicators gun to gun

[Tree Rat]

So there I was banging out some 9mm 124's with my favorite WSF and Power Pistol loads when I noticed a pretty big disparity between the fired primers on the G-19 and the P226.

The primers on the G-19 were nice and convex with lots of radius around the edges. The primers from the P226 were noticebly flat with a good amount of breach face skid.

Obviously loads work in different guns in different ways, but what are some of the factors at play here that seem to raisie the presurre of a given load from gun to gun.....chamber dimension?.....headspace?....what about spring rates/slide velocity for lock and unlock?


TR

[Washington,D.C.]

In handguns "pressure signs" are normally not like they are with high power rifle cartridges. In semi auto pistols the unlocking of the action has the largest effect on primer appearence. Part of this is the design of the pistol. A big part of it is the weight of the recoil spring. I have seen chamber dimensions effect pressure and pressure signs in rifles but I'm not sure it shows so much in pistols but it might. The Sig firing pin strikes the primer quite a bit harder/heavier than the Glock. I have found with certain primers and certain loads that the primer strike can effect pressure and velocity. I know it shouldn't but I think the lower pressure strikes might be a slightly less than ideal primer strike. I found this by switching hammer springs in some pistols.

[918v]

TR,

Do this:

Measure the case expansion in your Glock. Compare a factory load to your handload using the same case. Repeat this test with your Sig. If your handload expands the case to the same degree as factory, or less, then you are OK. If your load expands your case more, then you are exceeding max pressure guidelines.

Primer appearance and tool marks imparted by the chamber are deceptive. As you can see, the same load appears radically different from gun to gun. I bet you that case expansion, when compared to factory loads, isn't so different.

[Crazy4nitro]

This is why I work-up loads in Each of my Guns separately if I'm going any higher then Bunny Fart level.

'Nitro

[MakeMineaP99]

This is why I work-up loads in Each of my Guns separately if I'm going any higher then Bunny Fart level.

'Nitro


Further, even if you have two identical firearms, differing only in serial number, work up the loads, EVERY firearm is different.

[Steve Koski]

I've seen some factory ammo fired by the cops with hellish breech face skid. Not sure what they fired it in. It still reloads and shoots fine. In fact, I wish they'd leave more of it on the ground for me.

[MakeMineaP99]

What caliber? I bet it come out of a subgun.

[Steve Koski]

.40

[MakeMineaP99]

Have flute marks on it?

Most subguns are either 9s or .45s.

[freakshow10mm]

Yup. I work up loads and test them in all guns for that caliber. I load to the hottest that all guns take without pressure sign.

[chewy]

I just smuge myself with Sage before I shoot any of my loads.

[Steve Koski]

No flute marks on the .40 brass with heavy wipe marks. That's other good 40 brass.