What Does Single-Action Mean?


Many shooters who’ve been around the block a couple of times will immediately know what “single-action operation” means, but some new shooters might not. We’ll bring everybody up to speed below:

What Are Single-Action Only Triggers?

Single-Action Only (SAO) triggers are found on many types of firearms. An SAO trigger requires the hammer of the firearm to be cocked before the pistol can be fired. SAO triggers are found on both revolvers and semi-automatic pistols as well as lever-action and semi-automatic rifles and most shotguns.

As the SAO trigger name suggests the trigger has one, single action or movement. The user must cock the hammer by commonly using the thumb of their shooting hand to cock back and lock hammer fully rearward. The user then presses the trigger to fire the gun. In many cases an  SAO trigger provides a crisp and clean trigger break and that is why it is used with by many competitive bullseye shooters who need to precisely hit a small target or bullseye. Let take a look at different types of guns that use an SAO trigger.

What is a Single-Action Revolver?

Single-Action or SA revolvers are what is commonly referred to as cowboy guns. These guns are the first revolvers to be designed. In fact, Samual Colt envisioned the single-action revolver in the 1830s and went on to build a very successful revolver manufacturing company that still bears his name today. These first revolvers proved to be well made, reliable and accurate. The single action revolver concept is simple in hindsight. Use a cylinder with multiple chambers that rotes each time the hammer is cocked. The hammer must be manually cocked each time to fire the revolver. Watch any western movie or show and you will see single action revolvers in use. While the term SA or single-action is most commonly used for these revolvers they also fall into the category of a gun with an SAO trigger.

What Are Single-Action Only (SAO) Pistols?

SAO pistols are hammer fired semi-automatic pistols like a 1911-style pistol or a Ruger MK IV rimfire pistol. To fire a pistol with an SAO trigger, the hammer must be fully cocked before the trigger can be pressed to fire the pistol. In the case of a 1911 style pistol, the hammer is exposed and can be cocked back by the shooter using their thumb or the slice can be retracted to cock the hammer. In the case of the Ruger MK IV the hammer is enclosed inside the gun and the bolt is retracted to cock the hammer. With semi-automatic guns the cycling of the action automatically cocked the hammer for the next shot.

What Does SAO Mean In Other Firearms?

Many rifles use SAO triggers. Lever-action rifles like Winchester Model 1873 and Marlin 1895 rifles have an exposed hammer that can be cocked by the user using their thumb or the hammer can be cocked by cycling the lever. Each time a lever-action rifle is fired, the lever must be cycled to cock the hammer and load a cartridge into he chamber. Semi-automatic rifles like the AR-15 platform and Savage A22 and Model 64 rimfire rifles all use an SAO trigger. The hammer on semi-automatic rifles is enclosed inside the gun and with each press of the trigger, the rifle fires, cocks back the hammer, ejects an empty case and loads a new cartridge.

Shotguns like single-shot, break action shotguns and semi-automatic models use an SAO trigger. In all cases, no matter the firearm type, an SAO trigger requires the hammer to be cocked before the gun can be fired.


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