Measuring firing pin protrusion can identify one reason for light primer strikes and misfires. Here’s how I made my own gauge.

by Roy Seifert

In American Gunsmith January 2021, author RK Campbell’s article “Firing Pin Logic and Mechanics” discussed firing pin protrusion as being a potential cause of misfires and light primer strikes. If the firing pin does not strike the primer deep enough to crush the priming compound against the anvil and cause ignition, a misfire occurs. If the firing pin protrudes too far it can pierce the primer and cause blowback or other problems.

SAAMI defines firing pin protrusion as, “The distance the firing-pin protrudes from the breech face when it is in its most forward position.” Brownells provides some general rules for firing pin protrusion. Centerfire rifles and handguns usually measure between…

Read more in the April 2021 issue.

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