F.P. protrusions

mtnsmith · November 20, 2009, 10:02 AM

does anyone have a chart on what the firing pin protrusions should be be on most guns? I have never seen one..Would like to have some kind of guide since I am new at this..

mtnsmith

James K · November 20, 2009, 04:12 PM

It varies with the gun design, but .06-.07" would be a good average. It doesn't matter if it is a bit too long if it doesn't protrude and either interfere with feeding or cause the gun to fire when the bolt/breech closes.

Just FWIW, too much protrusion does NOT cause "pierced" primers. Unless the firing pin has a needle nose, no firing pin spring ever made has enough power to actually pierce the primer. So-called "pierced" primers are caused by too light a firing pin or firing pin spring, when the pressure forces the firing pin back and pushes a disc of primer metal back into the firing pin hole.

Jim

November 20, 2009, 10:02 AM	#1
mtnsmith Member Join Date: November 17, 2009 Location: idaho Posts: 29	F.P. protrusions does anyone have a chart on what the firing pin protrusions should be be on most guns? I have never seen one..Would like to have some kind of guide since I am new at this.. mtnsmith

November 20, 2009, 04:12 PM	#2
James K Member In Memoriam Join Date: March 17, 1999 Posts: 24,383	It varies with the gun design, but .06-.07" would be a good average. It doesn't matter if it is a bit too long if it doesn't protrude and either interfere with feeding or cause the gun to fire when the bolt/breech closes. Just FWIW, too much protrusion does NOT cause "pierced" primers. Unless the firing pin has a needle nose, no firing pin spring ever made has enough power to actually pierce the primer. So-called "pierced" primers are caused by too light a firing pin or firing pin spring, when the pressure forces the firing pin back and pushes a disc of primer metal back into the firing pin hole. Jim