7.62x25mm bulging primers


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stressed
October 13, 2013, 11:40 PM
sighted in my PPS for the first time this last weekend, all of the primers on the casings were bulged as if high pressure. Chamber looked fine, cleaned it out with same results. Bolt face appeared fine, disassembled and pin was fine. Don't have another to compare it.

Factory new ammo (which was really dirty) S&B FMJ and PPU hp's, both 85 grain.

Chronoed both rounds (9.5" barrel)

1800 fps average for S&B FMJ 85grn
1550 fps average PPU hollowpoint 85gr

Yeah the S&B is pretty hot but the PPU had bulged primers as well, all of them.

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wally
October 14, 2013, 06:20 AM
Photos of the bulges?

If the firing pin tip is much smaller than the firing pin opening in the bolt face you will often get a "creator" with a ring around it where material has flowed around the firing pin and back into the opening.

stressed
October 14, 2013, 11:37 PM
http://i250.photobucket.com/albums/gg241/mrtwodoorcoupe/20131014_182707-1.jpg (http://s250.photobucket.com/user/mrtwodoorcoupe/media/20131014_182707-1.jpg.html)

GBExpat
October 15, 2013, 08:36 AM
Looks like wally had the answer for you.

wally
October 15, 2013, 09:27 AM
Lets see a photo of the bolt face to confirm. I'd expect to see a lot of space around the firing pin when it protrudes a bit from the bolt face.

I don't think I've ever seen a bolt face opening that was that close to the diameter of the primer.

stressed
October 21, 2013, 01:36 AM
I don't have a photo, but there is not that much space in the firing pin hole on the boltface and the firing pin.

Any other ideas?

MachIVshooter
October 21, 2013, 02:07 AM
Any other ideas?

Headspace issue, maybe; the firing pin is trying to hold the case forward by the middle of the primer.`

Let's see a pic of your bolt face.

stressed
December 8, 2013, 03:32 AM
http://i250.photobucket.com/albums/gg241/mrtwodoorcoupe/20131207_012352.jpg (http://s250.photobucket.com/user/mrtwodoorcoupe/media/20131207_012352.jpg.html)

5-SHOTS
December 8, 2013, 10:01 AM
Do the primers look worst than the ones fired by a modern Beretta pistol?

barnbwt
December 8, 2013, 10:54 AM
That looks really big. Most conversions drill out the pin and replace it with an AR15 sized pin (if not that actual FP), leaving the remainder of the drilled fixed pin to act as a FP bushing. Yours looked like they removed the whole fixed pin and replaced it with a similar sized moving pin; recipe for unsupported primers at the edges. Doesn't necessarily make for unsafe operation, but it also unnecessarily stresses the primer cups.

TCB

wally
December 9, 2013, 09:27 AM
From the photo the firing pin looks on the small side for the hole diameter. But as long as the primers aren't piercing and the empties are ejecting I'd not worry about it unless you start reloading -- might affect your primer choices.

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