M96 rupturing primers

[CINDERS]

S & B 303 brass never lasted more than 2 reloads sometimes just one in my rifles , the H/S on my 303's snug nicely at .067. I have .064 but do not use it. My R.P brass some of it is up to 12 reloads and going strong I just annealed a batch as I fls all my brass for them as reloading for 5 different 303 rifles it is easier to just FLS. Allot of my friends have had same results with S&B.
I would have thought in the miliseconds on detonation of the main charge (Not the primer as it initially backs out when detonated) that the case would grip equally in all directions! As #3 suggests I would try a different brand of ammo and see if that has the same result then you have a bit better understanding (hopefully) as if it does not do it the ammo could be the issue if it does the same to another brand then it is the rifle. The F.P protrusion needs to be checked also the radius of the firing pin head that strikes the primer it may be to sharp!

If you had left the ammo out in the car overnight ready for a quick scoot in the morning the metal may have been brittle due to minus 30 degree temps may have caused issues I am no metalurgist others may have had experience at -30 degree temps with ammo. Jim does it get that cold up in Canada!

On a shooting course I attended we had hot/cold ammo velocity tests the ammo I fired had been heated to 50 degrees C in my 6.5 x 284 they were hot reloads before the heat up the primers backed way out with some gas escape I only fired 2 rounds both the same result and called it quits for doing that as the SAAMI of 60,000psi limit for that round would have been surpassed I reckon
The Mag chrony clocked the 140 Berger's doing 3,070FPS & 3,064FPS according to my records had a good E.S I suppose 6fps .

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[browningautorifle]

Jim does it get that cold up in Canada!

Of course it does. In Alberta, when we did field firing in the winter and the troops were living out we'd have everything out there through the night and beyond. The ammo would be stored at outside temp in unheated buildings too. No heaters to give temp change...that would cause condensation. Brittle brass is brittle brass. Too, if ammo has been handed around through it's life like much of the 8MM and .303, some of the .30 Carbine and .30 M2 ball has...then the heat and time it's endured can break down components causing the exact reactions described. We've all had them happen with .303...hangfires, popped primers...and brass.