I have a Martini .22 that left a very shallow firing pin indention on cases, although I never had a failure to fire. On inspection, I noted that it appeared to have broken off, leaving a flat with less than 0.015" protrusion.

I got a replacement pin, installed it, and found it had over 0.070" protrusion. That seems quite excessive, so I dug out my other Martini and found it had the same protrustion.

What shoul be the protrusion for a .22? I'm assuming something less than 0.040".

Also, what is the best shape for the firing pin? I remember reading of preferences for a rectangular shape, but have been unable to find those references.

Clarence

Just less than the depth of rim groove on your rifle. If its a min head space gun (.043") then protrusion should be .038 to .041 of an inch.

The shape should be chisel tipped (30degree included angle) with a .020" to .025" wide flat. If you can taper the chisel tip back about .005" to .010" from the center of the cartridge to the outer rim, that is generally considered the best for consistent ignition.

Thanks, Rusty!

Clarence