7.62x54r primer Extruding into firing pin holes

[Dark Helmet]

Shooting up some JMS 02 surplus and having the same problem with j-word reloads. Finn M39. Not cratering but definitely raised up around the firing pin indentation in the fired primers. Is this common in Moisins?

[littlejack]

A lot of the firing pin holes in the MN rifles are oversize. I would guess this is the problem but cannot be positive. I see a lot of the fired 7.62x54 cases at the range and most of them have what you discribe.
Jack

[nicholst55]

You could always send your bolt out and have the firing pin hole bushed, and the FP tip turned down to match. Assuming someone will do this work on a Mosin, that is. Of course, it would cost about the same as another Mosin...

Perhaps a new bolt head would help?

[Rockydog]

Perhaps it needs adjusting. I've never adjusted mine but I have watched this. RD

http://www.youtube.com/user/disneyland1980

[Phat Man Mike]

if you have the tool that was standard issue with the M/N there is a spot that you use to check your firing pin ! it's easy to set ! IMO:wink:

[VintageRifle]

Remember, these are military weapons. They have strong striker springs to help make sure they set off any type of primer in any type of extreme environment. Just about every mosin nagant I have fired will do this to the primers.

[Gtek]

I am a newbie to cast world, but the Russian bores are all over the place .310-.313. I have seen several Finn's .309. On my bench I would take that as a pressure sign. Any problems lifting bolt?

[Maven]

DH, All of the above advice is worth considering. Let me add that I had this problem and worse with factory loads in my M 28/30 Finn. Nagant. The factory rounds were of such high pressure that the primers were punctured, allowing enough gas into the action to "disassemble" the bolt. Neither I nor the gun was harmed, and I was able to reassemble the bolt, but I was a bit shaken, to say the least. What you first need to do is slug your bore and compare its diameter to that of the jacketed bullets. If the jacketed ones are too large, don't use them and see if you can swap them for something more suitable, say .310". If those dimensions are in agreement, measure the OAL of a factory round, pull the bullets and reduce the powder charge by at least 10%. Reseat the bullets to the same OAL as the factory round.