Sir,

I have a pre-64 M70 that is piercing primers at about 66.5 gr of IMR 4350 behind 225 Hornadays. Velocity is 2660 fps at 66.0 gr of 4350.

Barrel is a Krieger and is quite new.

Firing pin protrusion is a measured 0.060"

Nose of FP is not hemispherical but rather a flattened dome. Has a pretty square edge and shows signs of the slightest rivetting.

What should be the shape of the firing pin nose?

Where can I get a new FP spring for the rifle? Are any of the current Winchester springs appropriate? (I can get those through Brownell's.)

Thanks VERY much!

I looked at one pre 64 for you and the pin protrudes .060" and has the same flat top dome that you described. It's condition is not all that perfect either. This rifle has been fired with a very hot wildcat for 15 years and now it's a .264 WM and it has never pierced a primer.

Until Belk gets to it you might change primers?

What is the cartridge anyway?

It's a 338 Win Mag. Has done it with CCI 250 and WLMR primers. Now have some Fed 215's I could try ... but I expect this is not a primer problem.

I suspect the FP needs to be recrowned and the FP spring needs to be replaced.

So far no damage to the FP or to the bolt face ... and the practice loads are below the pierce point.

Should be able to get a lot more velocity out of this cartridge than am seeing. The rifle is Magnaported (real magnaport) ... that have anything to do with anything?

(Rifle was built to be an elk rifle for use in the mountains. Weighs just over 8 pounds with scope, sling, and ammo. About as much as I want to lug up and down steep hills ;>

mstarling,

.060 protrusion is fine, and if properly shaped, would not be the problem. A sharp or square edge on the firing pin nose may well be responsible for the ruptured primer. The firing pin nose should be round.

If you have access to a lathe, you can stone the nose as it spins. If not, you can use a drill press to spin it while you gently shape the nose. Try not to reduce the protrusion below .055.

Good luck,

Malm

You might try a different lot of primers. A few years back one lot of primers, I do not remember the brand, would burn through on the edge, causing a jet of hot gas to escape and cut a crater in the bolt face.

The FP protrusion on pre 64's came up not long ago and I recall checking another one and it had a little flat on it's nose also. If my memory is correct that one measured .063".

I agree with Malm. and I don't see why that flat is on the FP nose. It could even be polished by hand with 400 paper.

I do have some Remington 9 1/2's here that split on their outside corner and leak onto the bolt face. There must be 900 left, maybe more. I got a OK from Remington to return them and I never did. I wish these things would go away.

I would just polish the nose by hand without taking the spring off. Then change the primers. If that does not work get on the phone and find some springs. It's July already.

[ 07-03-2003, 20:49: Message edited by: Savage99 ]