When searching for the best firearm for you, it is crucial to recognize one thing: mission dictates gear. Your mission might revolve around concealed carry, competition, home defense, hunting, or law enforcement. Regardless of what it is, your firearm needs to meet, if not exceed, its intended requirements.

One question many people have when searching for their first firearm is, “what’s the difference between action types?” Today, we’ll focus on different trigger systems and explain common firearm actions.

What Does “Action” Mean When Discussing Firearms?

You can use the term “action” in several ways within the firearm community. It may refer to how a breech-loaded weapon loads, locks, fires, extracts, and ejects ammunition. It can also specify how ammunition is inserted into the firing chamber (break-action, bolt-action, lever-action, etc.)

“Action” can refer to the length of a bolt-action rifle’s receiver (short-action, long-action, magnum-action). Or it could identify a gun’s type of trigger function (single-action, double-action, etc.).

For this article, when we refer to a firearm’s “action,” we clarify the type of firing mechanism. Does pulling the trigger cock the hammer and rotate the cylinder to fire? Or does it simply release the hammer or striker?

Below, we’ll discuss the differences between single-action and double-action firing mechanisms (and the combination of the two).

Single-Action (SA) Trigger

A single-action (SA) trigger is the earliest design and is mechanically the most straightforward of trigger types. However, shooters did not use the term SA until the introduction of double-action revolvers in the mid-19th century. Before DA’s creation, all triggers were SA, including flintlocks, matchlocks, percussion rifles, etc.

Single-action means pulling the trigger performs one function—releasing the hammer or striker. If a single-action pistol isn’t cocked, pulling the trigger does nothing. Shooters must pull the hammer back manually and then squeeze the trigger to release it.

Cocking the hammer rotates the cylinder, aligning a new round with the barrel. Once cocked, the shooter squeezes the trigger to fire. After firing, the hammer must be re-cocked to fire additional rounds.

Because the shooter pulls the hammer back before firing, a single-action handgun will have a lighter, shorter trigger pull than a double-action. A popular example of a SA revolver is a Ruger Blackhawk, although the most well-known SA pistol is the Colt 1911.

Double-Action (DA)

Generally, this type of action refers to revolvers. With double-action, the trigger performs two actions. It cocks the hammer or striker and fires the firearm.

Many revolvers are thumb-cocked and fired in single-action mode, while others have enclosed hammers and fire only in double-action mode. In double-action revolvers, the entire hammer is shrouded, or the thumb spur is machined-off, preventing the user from cocking it.

In DA semi-automatics, no internal mechanism can hold the hammer or striker in a cocked position. Every shot is in double-action mode, and the hammer will not remain cocked after the first round fires.

Double-action firearms have a longer, stiffer, or heavier trigger pull than single-action weapons. This difference is due to the trigger’s extra work of cocking the hammer. Colt’s Python series and Dirty Harry’s iconic Smith & Wesson Model 29 are two examples of traditional DA revolvers.

Double-Action-Only (DAO) Triggers?

Like the double-action, a double-action-only (DAO) is a design where the trigger performs two functions. It cocks the hammer and rotates the cylinder to fire the piece. Shooters may repeatedly fire by pulling the trigger until all rounds are gone.

However, unlike a traditional DA, you cannot manually cock the hammer of a DOA firearm. The DOA design only activates the mechanism when you pull the trigger. Even if you own a semi-automatic handgun with an external hammer, the hammer will safely return to its forward position after each shot if it is a DAO variant.

The Smith & Wesson 640 is a double-action-only pistol. This design requires a longer, heavier trigger pull to cock and trip the hammer/striker for every shot. There is no single-action function in this mechanism. The hammer or striker will rest in the down position until you pull the trigger.

Double-Action/Single-Action (DA/SA) Trigger

You guessed it! A double-action/single-action (DA/SA) firearm combines features of both double and single-action mechanisms. A DA/SA weapon utilizes two different trigger pulls. The first is a longer, heavier pull that cocks and releases the hammer to fire. After the first shot fires, the slide reciprocates and recocks the weapon making the trigger light and short.

An example of a DA/SA semi-automatic firearm is the Beretta 92 series. A DA/SA gun provides the positive aspects of a single-action trigger without having to carry “cocked and locked” (loaded chamber, cocked hammer). Users also avoid carrying with an empty chamber, which would require them to chamber a round before firing.

In a DA/SA firearm, the cycling slide automatically cocks the hammer to the rear when the gun discharges. The remaining shots will be in single-action mode unless the shooter manually lowers the hammer again. This motion is also known as traditional double-action (TDA).

Unlike a single-action semi-automatic, a shooter can carry a pistol with the hammer down on a loaded chamber. When ready to fire, simply pulling the trigger in double-action mode will cock and release the hammer. This action combines with the ability of most semi-automatics to self-cock the hammer when firing.

DA/SA typically refers to semi-automatic firearms. However, the trigger mechanism function of a DA/SA semi-automatic handgun is identical to a DA revolver. In the case of a revolver, double-action means the firearm can fire both double and single-action. A typical DA/SA revolver can fire single-action but uses double-action as a default.

Single-Action vs. Double-Action: Which Trigger Do I Choose?

Some believe that single-action handguns have better triggers than double-action guns because they don’t have to overcome the added resistance of cocking. A single-action trigger tends to be lighter and crisper than other types. To many, especially new shooters, this makes shooting single-action firearms easier.

Due to their light triggers, single-action firearms almost always have manual safeties to prevent unintentional discharges. In the case of a single-action revolver, a large hammer must be manually thumb-cocked for each shot.

Others argue that the long, heavy pull of DA and DAO triggers make it harder to fire the gun unintentionally. Those who prefer DA revolvers find that they can fire by pressing the trigger or manually cocking the hammer to enjoy a short trigger pull, excellent for accuracy. The advantage of a DAO pistol is its consistent trigger pull, simple function, and lack of external safety mechanisms. Simply put, it is more accessible to cock and fire.

Military and law enforcement seem to favor the DA/SA pistol. However, if you choose a DA/SA, you must master two types of trigger pulls. The first shot will require a long, heavy trigger pull, while subsequent ones will have a short, crisp trigger break.

Ammo Planet Has Your Back

Any transition from DA to SA will affect accuracy until you become familiar with your firearm. The key here is training. Learning proper trigger discipline and precision conditioning are vital fundamentals. Fire a variety of handguns before purchase to identify which feels best to you.