Rifleman Q&A: Double-Action, Single-Action, DA/SA, DAO & Striker-Fired

by
posted on March 22, 2016
** When you buy products through the links on our site, we may earn a commission that supports NRA's mission to protect, preserve and defend the Second Amendment. **
qanda.jpg

Q: I notice that you often use “double-action,” “single-action” and sometimes even “striker-fired” to describe triggers on handguns. I’m a new member, can you give me the executive brief on what these terms mean?

A: As handgun designs have evolved, the nomenclature used to describe their operation has not kept up. Essentially, the terms we use to describe trigger operation were nailed down before semi-automatic pistols were invented, so we will start with revolvers. Single-action revolver operation requires that the hammer be manually cocked by the shooter for each shot. Examples include the Colt Single Action Army and Ruger Blackhawk. In double-action revolvers, a single trigger pull both cocks the hammer then releases it. Most can also be fired single-action by manually cocking the hammer. The majority of revolvers today, such as the S&W Model 10 and Ruger GP100, are of such design. But there are also double-action-only (DAO) revolvers in which pulling the trigger cocks and releases the hammer with no provision for single-action operation. Some have external hammers with their hammer spurs removed, such as Taurus’ Model 85CH, while others, including the ubiquitous S&W Model 442, have a shrouded, or internal, hammer.

It gets more complicated for semi-automatic pistols. For a single-action semi-automatic, the external hammer must be manually cocked for the first shot. (Of course that typically occurs when the first round is chambered by the shooter as he retracts and releases the slide.) For subsequent shots, the cycling of the slide cocks the hammer each time the gun fires, as in the Colt Government Model. For double-action/single-action (DA/SA) pistols, the first shot is either fired in double-action mode using a long, heavy trigger pull to cock and release the hammer, or, the hammer can be retracted manually and the gun fired as a single-action. Subsequent shots cock the hammer by slide movement and fire using a markedly lighter single-action trigger pull. Most pistols that operate this way have external hammers, and a good example is the Beretta Model 92FS or U.S. M9. A semi-automatic pistol with a double-action-only trigger operates like a DAO revolver—giving the same trigger pull length and weight each time. Such guns, like the SIG Sauer P226R, have no provision for single-action operation. 

But the most common form of trigger operation in new hammerless designs involves the use of an internal striker and a trigger that is the same pull weight and length every time. Such systems partially (or even fully) pre-cock the striker to reduce pull length and weight, and often mechanical safeties are integral to the trigger design (such as on Glock pistols). Some guns that operate this way only use trigger movement to clear safeties and release the striker—no cocking occurs. Although the trigger’s pull length and weight are closer to that of a single-action, they still operate like a double-action-only revolver in that all that is necessary to fire is to pull the trigger. To keep things simple for gunwriters—and magazine readers—such guns are often called double-action-only, when striker-fired may actually be a more proper description.

A fuller treatment of handgun triggers has been written by Field Editor Wiley Clapp and can be found at americanrifleman.org/triggernometry.

Latest

Gotw Wilson Combat Divison 77 Project 1 Web
Gotw Wilson Combat Divison 77 Project 1 Web

Gun Of The Week: Wilson Combat Division 77 Project 1

Join American Rifleman staff on the range in this video to get a closer look at Wilson Combat’s somewhat cryptically named “Division 77 Project 1.” 

The Armed Citizen® July 18, 2025

Read today's "The Armed Citizen" entry for real stories of law-abiding citizens, past and present, who used their firearms to save lives.

Review: POF-USA LMR BASE Rifle

The Patriot Ordnance Factory LMR Base offers a .308 Win. chambering in a lightweight, AR-15-size package, which makes it a capable platform for today's new gun owner. And it comes at a fair price.

2025 Accessory Of The Year: Wyoming Sight Drifter

For each of the past 23 years, the editors of American Rifleman have convened to select our top picks for the past year’s best and most innovative products. Here are the most recent winners.

Henry Donates Rifles To Support Young Leukemia Victim

Henry Repeating Arms has donated a limited run of 50 “Team Keane” Golden Boy .22 lever-action rifles to support 13-year-old Keane Rhodes of Universal City, Texas, who is currently undergoing aggressive treatment for ALL T-cell leukemia.

Rifleman Review: Springfield Armory Echelon

Springfield Armory introduced its Echelon in 2023, bringing a modernized, chassis-style, striker-fired handgun to the market that has since seen several notable line extensions.

Interests



Get the best of American Rifleman delivered to your inbox.