Firing pin - how long??

[HemiRambler]

Ok I was at the gun show this weekend (diligently looking for a lever mind you) when this orphaned .22 pump followed me home. I didn't give much for it and it appears to have a decent bore so I figured I'd have some fun trying to make some of the missing parts.


I have it apart - the firing pin is broken - looks like an easy enough lathe project.

So... how long should I make it? I mean I can measure the breech block, but how long is too long?

Is this a simple matter of measuring the strike depth on a spent round and just adding that to the length of the breech block or is there some additional kentucky windage I should consider?


It's a later Remington Model 12

Thanks !!

[Griff]

From Numrich (Gun Parts Inc.):
8 100850 Firing Pin (Round) $19.05
8 100050 Firing Pin (Square) $32.95

[piller]

Perhaps it wouldn't be as much fun, but I'd probably go with the replacement parts from Numrich.

[KCSO]

At maximuum depth the firing pin can NOT touch the face of the breech. A good rule of thumb is 3/4 the distance from bolt face to breech face but if you are really technical Brownells sells a nice book for $75 that gived the dimensions of most firing pins on modern guns.

[HemiRambler]

Thanks for the replies!

So ask another question....define "maximum depth"?

By that I mean the the firing pin will actually travel about .010" past the surface of the breech block. So do you include that .010" or do you only measure it when it's flush?

It seems to me that flush plus the 3/4 rule makes the most sense. Then just double check that it can't touch the breech face and I am golden - famous last words - right?

So far I made it from an allen head bolt, but have some slight concerns on the hardness - they say they are "thru hardened" but they are definitely softer in the center versus the outside of the part. I'd take a swag and call it 28 or 30 Rc.

Will this provide good service life or should I consider trying to harden the tips further???

Thanks!!! for your thoughts!

[KCSO]

When it hits the breech face it's too darn long! Peening the breech face ruins the chamber.

[HemiRambler]

Well, here's the finished version - decided it was hard enough to at least try out. Put a spent case and test fired it - looks to be striking the cartridge fine - will know for sure when I fix the other issues.

Fun fun fun.

[Griff]

Nicely done. Let us know if successful.