failed primer, fed 210

[rsmithsr]

gentlemen, i was shooting a 1943 mosin nagant 91/30 rifle this week when i had a primer fail, as in a hole in the cup, allowing gas out thru the bolt area. the load had ben shot before. est pressure is only 48k, bullet a sierra match king 174/312, powder is 43.4 of n135 producing a velocity that day of 2632. higher than expected but not gross. these are older narrow red box with a printed lot number of A-6272...i have used a bunch of them with no issues in several rifles. so just a random failure ? comments ideas ?? not the best pic, but not a firing pin issue, edge of the cupp

 

[243winxb]

Random failure i hope. I had some defective Rem 9 1/2 many years ago. Two years ago some Win SPM . Happens in all brands, soon or later.

There is now a guage to check pocket diameters.

If the primer pocket is loose, gas will come up the side of the primer & make a hole, in primer.
Should see on the side of the primer.

A defective primer will look almost the same.

Both may pockmark the bolt face.

 

[DHuffman]

Initially I thought it probably had more to do with pin fall and or shape/condition of the tip of the pin I'd bet.

After looking at the pic I see it pierced on the edge so likely a defective primer but they are still flowing back around the pin it looks like.

 

[donna1205]

Primer Defect – Since you’re using older primers, it’s possible this was just a random manufacturing flaw in the cup metal, leading to a thin or weak spot that ruptured under pressure.
Sprunki