doubleaction

Double-action is a term used in firearms to describe a trigger mechanism in which a single pull of the trigger cocks and releases the hammer or striker, firing the chambered round. This is distinct from single-action systems, where the user must manually cock the hammer before each shot and the trigger only releases it.

In double-action revolvers, the trigger pull cocks the hammer and rotates the cylinder as part of the same motion, allowing the shooter to fire without manually cocking. Many double-action revolvers also offer a manual hammer-cocking option for a traditional single-action shot, though some are designed as double-action-only (DAO), requiring a complete trigger stroke for every shot.

In semi-automatic pistols, the term often applies to double-action/single-action (DA/SA) designs. The first trigger pull cocks and releases the hammer (double-action). After the pistol’s slide cycles, the hammer is re-cocked by the action, so subsequent shots are typically single-action with a lighter trigger. Some pistols are configured to be double-action-only, providing a consistent, heavier trigger across all shots and lacking a distinct single-action mode.

Historically, double-action mechanisms appeared in the late 19th century as an alternative to purely single-action designs, with revolvers from manufacturers such as Colt and Smith & Wesson helping popularize the concept. The term now covers a range of designs and trigger strategies across revolvers and semiautomatics.