Editing Revolver (section)

===Double-action===
[[File:Anaconda-502.jpg|thumb|[[Colt Anaconda]] .44 Magnum double-action revolver]]

In double-action (DA), the stroke of the trigger pull generates two actions: 
#The hammer is pulled back to the cocked position, which also [[Indexing (motion)|indexes]] the cylinder to the next round.
#The hammer is released to strike the [[firing pin]]. 
Thus, DA means that a cocking action separate from the trigger pull is unnecessary; every trigger pull will result in a complete cycle. This allows uncocked carry, while also allowing draw-and-fire using only the trigger. However, this will require a longer and harder trigger stroke, though this drawback can also be viewed as a safety feature, as the gun is safer against accidental discharges from being dropped.<ref name="forensic" /> The sole mode of operation was seen as reducing training time for the British Army in WWII where the revolver usage was rapid fire at very close ranges.<ref>Wilson, Royce, "A Tale of Two Collectables", ''Australian Shooter'' magazine, March 2006.</ref>

Most double-action revolvers may be fired in two ways:<ref name="forensic" />
# The first way is single-action; that is, exactly the same as a single-action revolver; the hammer is cocked with the thumb, which indexes the cylinder, and when the trigger is pulled, the hammer is released and the round is fired.
# The second way is double-action, or from a hammer-down position. In this case, the trigger first cocks the hammer and revolves the cylinder, then trips the hammer at the rear of the trigger stroke, firing the round in the chamber.

[[File:Albion revolver.jpg|thumb|[[Enfield No. 2]] Mk I* double-action-only revolver. Note the spurless hammer.]]

Certain revolvers, called ''double-action-only'' (DAO) or, more correctly but less commonly, ''self-cocking'', lack the latch that enables the hammer to be locked to the rear, and thus can only be fired in the double-action mode. With no way to lock the hammer back, DAO designs tend to have ''bobbed'' or ''spurless'' hammers, and may even have the hammer completely covered by the revolver's frame (i.e., shrouded or hooded). These are generally intended for concealed carrying, as a hammer spur could snag when the revolver is drawn from clothing, but this design may result in reduction in accuracy in aimed fire.<ref name="Sween2004">{{cite book|last=Sweeney|first=Patrick|author-link=Patrick Sweeney (gunsmith)|title=The Gun Digest Book of Smith & Wesson|url=https://books.google.com/books?id=eBxEBgJBG0MC&pg=PA284|year=2004|publisher=Gun Digest Books|location=Iola, Wisconsin|isbn=0-87349-792-9|page=284}}</ref>

DA and DAO revolvers were the standard-issue sidearm of many police departments for many decades. Only in the 1980s and 1990s did the semiautomatic pistol gain popularity after the advent of [[safe action]]s. The reasons for these choices are the modes of carry and use. Double-action is preferred in high-stress situations because it allows a mode of carry in which one only has to draw and pull the trigger—no safety catch release nor separate cocking stroke is required.<ref name="Sween2004" />