Looking to make a 22 BR on my model 12. Other than doing a bushing job, can you get a small pin holed bolt head? Which leads to the question; what size pin does the LRPV use in the 6 BR config? If it's .062 or so can a swap be made w/the 12? Thanks, Duke.
And the FAQ section didn't have the answer.
50 views and no love? Folks, i'm just trying to gain a little knowledge here. Am in the process of getting all the mic's gauges and whatnot to build a 22BR and am unsure if i'll be able to get best velocity from this platform w/o resulting to bushing the hole or finding a "drop in" bolthead that already has the .062 hole that most accuracy guys say really help the higher pressure small primer cartridges; so help a brother out?
The different firing pin sizes only affect the diameter of the hole in the shank of the bolt head and the diameter of the hole in the bolt head retaining pin.
If you have a large pin in your rifle and you get a small pin bolt head you can drill out the shank of the bolt head up to the vent.
A large pin bolt head will work fine with a small firing pin.
The hole large/small thing has nothing to do with the portion that protrudes from the bolt head and strikes the primer.
It was merely a change to keep the bolt head retaining pins from breaking.
"Muzzle velocity is a depreciating asset, not unlike a new car, but BC, like diamonds, is forever."-German A. Salazar
Now I think I know why noone is chiming in...I'm not concerned with the "retaining pin", I'm wanting to know what the size of the actual firing pin is and the subsequent hole it protrudes thru on the bolt face to strike the primer. Trying to prevent flow back into this hole from higher pressure loads that are common from this cartridge when pushing the heavies( 70-90 grains )
So it sounds like you want to fix a problem that you don't know for sure exists yet.
The blue prints specs on the pin diameter and hole size are .068" for the pin and .072" for the hole, but that doesn't mean that is actually what you have.
Primer cratering can also be attributed to the profile of the pin tip. Firing pins commonly have a full radius of .034", but the tip of the pin will penetrate the primer cup no more than .025", leaving the tangent of the radius below the bolt face. This creates an unsupported gap around the pin and a place for primer cup material to flow.
Recut the radius of the pin tip to .020", so when it protrudes .025", it has a square juncture.
If your pin is less than .068" and the hole is bigger than .072", I would just go ahead and bush it.
Redo the pin tip first, if that don't work, then bush it.
"As long as there's lead in the air....there's still hope.."
Now THAT'S the kind of answer I was hoping to find! Thank you Sharpshooter! I know of others that have had problems of this nature and I was just thinking i'd head it off at the pass; your figures confirmed what I was thinking. Thanks again.
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