Firing Pin - Firing Pin Construction

Firing Pin Construction

The typical firing pin is a small rod of steel, with the end that strikes the primer rounded into a hemispherical shape and hardened. The rounded end ensures the primer is indented rather than pierced, as would happen if the firing pin were sharply pointed. Most firing pins have a spring to push them out of contact with the primer, and often will have an integrated passive safety mechanism, such as a block that prevents them from moving forward unless the trigger is depressed, or a transfer bar, also trigger actuated, that must be in place to allow the hammer to depress the firing pin. This safety is in addition to any manually operated safety or safeties that act to block the trigger or hammer.

Firearms that use long firing pins, such as pistols, will often use a firing pin that is too short to project when depressed flush by the hammer. This type of firing pin, called an inertial firing pin, must be struck by a full fall of the hammer to provide the momentum to move forward and strike the primer. If the hammer is down, resting on the firing pin, it is very unlikely that a blow to the rear will provide enough energy to the firing pin to detonate the primer. Most variants of the M1911 pistol use this type of firing pin.

Many firing pins are stamped from sheet steel, forming a rectangular cross-section rather than a round one. These will often have a cylindrical section at the front rather than a hemispherical one, and are fairly common in rimfire firearms. Sturm, Ruger, for example, uses sheet metal firing pins in its 10/22 carbine and Mark II pistol.

High performance firing pins are often made from lighter materials than steel, such as titanium. The lighter material increases the speed at which the firing pin travels, and reduces the lock time, or the time from trigger pull to the bullet leaving the barrel. See accurize for more information.