Hammer (firearms)

The hammer is a part of a firearm that is used to strike the percussion cap/primer, or a separate firing pin, to ignite the propellant and fire the projectile. It is so called due to the fact that it resembles a hammer in both form and function. The hammer itself is a metal piece that forcefully rotates about a pivot point.

The term tumbler can refer to a part of the hammer or a part mechanically attached to the pivot-point of the hammer, depending on the particular firearm under discussion (see half-cock). According to one source the term tumbler is synonymous with hammer.