Double action (or double-action) refers to one of two systems in
firearms
A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see Legal definitions).
The first firearms originated in 10th-century China, when bamboo tubes c ...
where the
trigger
Trigger may refer to:
Notable animals and people
;Mononym
* Trigger (horse), owned by cowboy star Roy Rogers
;Nickname
* Trigger Alpert (1916–2013), American jazz bassist
* "Trigger Mike" Coppola (1900–1966), American gangster
;Surname
* Bru ...
both cocks and releases the
hammer
A hammer is a tool, most often a hand tool, consisting of a weighted "head" fixed to a long handle that is swung to deliver an impact to a small area of an object. This can be, for example, to drive nails into wood, to shape metal (as w ...
.
*
Double-action only (DAO) firearms trigger: The trigger both cocks and releases the hammer. There is no
single-action function and the hammer will return to its decocked position after each shot.
**Double Action Kellerman (DAK): A variant of traditional double-action used on certain
SIG Sauer
Several brother companies that design and manufacture firearms use the brand name SIG Sauer . The original company, ''Schweizerische Waggon-Fabrik'' (SWF), later ''Schweizerische Industrie-Gesellschaft'' (SIG), went through several selloffs, ...
semi-automatic pistols. DAK triggers have a long stroke with pull. However, if a user shooting under stress short-strokes the trigger by only releasing it halfway, the trigger will reset, but with a pull. This temporary increased trigger pull is intended to prevent negligent discharges.
*
Traditional double-action
A trigger is a mechanism that actuates the function of a ranged weapon such as a firearm, airgun, crossbow, or speargun. The word may also be used to describe a switch that initiates the operation of other non-shooting devices such as a trap ...
– or double-action/single-action (DA/SA) – firearms trigger: The trigger combines the features of both a double-action only and a single-action only trigger.
** With a
revolver
A revolver (also called a wheel gun) is a repeating handgun that has at least one barrel and uses a revolving cylinder containing multiple chambers (each holding a single cartridge) for firing. Because most revolver models hold up to six roun ...
using this action, the hammer can be cocked first (single action), or the trigger can be pulled and it will cock and release the hammer (double action). Once the gun has fired, the hammer stays in the decocked position until the hammer is re-cocked (single action), or the trigger is pulled again (double action).
** With a
semi-automatic pistol
A semi-automatic pistol is a type of repeating single-chamber handgun ( pistol) that automatically cycles its action to insert the subsequent cartridge into the chamber (self-loading), but requires manual actuation of the trigger to actuall ...
using this action, the initial trigger pull will cock and release the hammer (double action). The
blowback from the firing mechanism automatically re-cocks the hammer after the gun is fired, such that each subsequent shot only requires the hammer to be released (single action). A
decocker
Close-up shot of a safety of an M16A2 rifle
In firearms, a safety or safety catch is a mechanism used to help prevent the accidental discharge of a firearm, helping to ensure safer handling.
Safeties can generally be divided into subtypes suc ...
, if present on the pistol, can be used to return the hammer to its decocked position to prevent negligent discharges.
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