Firing Pin Logic and Mechanics

An overview of a critical but overlooked part of every firearm.

by RK Campbell

If there is an overlooked part in any firearm, it is the firing pin. The firing pin is an important part of ignition and also has a bearing on accuracy and lock time, yet shooters seldom think of it unless it breaks or gives trouble. There are also safety concerns with certain types of firing pins if the shooter isn’t schooled in floating firing pins. Recently I was entertained to a story about a customer who brought a rifle into a pawn shop. Let’s just say he isn’t a common gun owner and is of the type we could probably do without. He brought in a padded case containing an AR-15 rifle to pawn or sell. The shopkeep asked if the gun were loaded and the fellow replied that he didn’t think so. While wrestling the rifle from the case, he dropped the still-loaded magazine. My friend Gene took over, pulling the charging handle to the rear while keeping the muzzle pointed in a safe direction to clear the rifle – which ejected a live round!

We won’t go into the problems with keeping a rifle chamber loaded in the home or the idiocy of bringing the piece into a shop loaded, but something else was curious. The cartridge extracted from the chamber had a distinct firing pin indent. Gene wondered how that happened. To told him to count the rounds in the magazine, betting there were thirty. There were. The only answer I have is the fellow had hand-fed a cartridge into the chamber and let the bolt slam, resulting in a firing pin mark on the primer from the floating firing pin. While we know not to load an AR or M1A in this manner, not everyone does. This fellow was lucky and his poor gun safety is an accident waiting to happen. I know the difference between different types of firing pins and how they work. As I have dealt with firing pins I have developed a healthy respect for their function and the need to learn more about them. But I am still learning.

A problem with firing pins doesn’t become evident until we…

Read more in the January 2021 issue.

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