Primer Check.

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Right. Looks fine to me as well. 10.0 gr of Longshot behind a 115 gr FMJ. 1.275" OAL. 4.6" barrel. 1575 fps Avg. Feels like 1575 shooting it. It's a handful. I tried other things over the chrono, and they we're as expected. I think the chronograph is working fine. Have multiple scales, and 99% certain it is actually 10 gr. Hodgdon shows a max of 10.0 gr of Longshot with a 115 gr XTP. OAL is longer, which I was under the impression should pretty much always lower pressures. Different bullet though. Does not engage the rifling.
 
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There is obviously a great deal more pressure with that second load. How much did you jump up the charge?

I am seeing velocities higher than I would expect.
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I bet!
 
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The first one is 357 SIG. The second one is a 10mm load. The second load is 13.2 gr of Longshot behind a Nosler 135 with a Tula LP primer. Hodgdon doesn't have 10mm Longshot data for the Nosler 135. There is 40 S&W data, with the max being 11.5 gr. I think 13.2 is too hot. A 135 gr at 1700 fps! That's what it chronoed at out of a 4.6" barrel. I did start lower and will be using less powder. Supposedly 13.2 gr was pressure tested and found to be inside 37.5 kpsi but 1700 fps was not the velocity achieved.
 
The first one is 357 SIG. The second one is a 10mm load.
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Silly me, I didn't read the headstamps, or even the complete post! *sigh*

First primers on .357 Sig look great!

That 10MM primers looks bad IMO. 1700 FPS is definitely stout!
 
.357 looks some where between mild to moderate, which would be expected with Longshot in that particular application.

That 10mm load looks like it's running typical full pressures. I wouldn't call it high pressures, as in excessive, but certainly above moderate range, which would be typical in that particular application with Longshot.

I can't really tell due to the angle of the photo, but is that primer pierced? I don't think it is, but it almost looks like some gases escaped from the FP indent, and there also appears to be a dark spot on the edge of the primer cup, and some on the edge of the pocket too.

GS
 
Might want to buy some extra firing pins. (and maybe some extra strength firing pin springs) The firing pin isn't getting pulled back out of the way fast enough. Do that long enough and it may break the tip off. The pressure signs look OK (although by the time you can see the signs you're already over the line). You're getting some pin smear though. Is that a Glock?
 
I don't believe any of the primers were pierced. I write the charge weight with black sharpies on the caseheads and that is probably what the black stuff is.
 
The edge of the primers looks fine, up there but fine.

The flow into the firing pin channel and the fact that the middle of the primer looks like it is indented, plus the tiny spot where it looks pierced (Nearly pierced?) gives me pause.
 
Well I called up Hodgdon to ask some questions regarding Longshot in the 10mm. I was curious why they didn't have any data for the Nosler 135 in the 10mm, but they did for 40 S&W. They stated it was due to Longshot being "too slow" for the 10mm with the 135s. I suggested they should test Longshot with the 135 in 10mm, but they didn't seem too interested. Hmmm.
 
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