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difference between single action double action and other mechanisms

What are Single Action, Double Action and Other Pistol Firing Types?

When trying to choose a concealed carry gun, one element to consider is that of the firing mechanism, as there are significant differences between them. Each has inherent benefits and each has inherent drawbacks.

It's a good thing to bear in mind while shopping for a concealed carry gun, as your choice will likely impact how well you practice your shooting, how often and also your opinion of your concealed carry pistol. You need to carry something you believe will work how you need it to when you need it to.

Single Action Pistols

double single action gun

The original type of firing mechanism and trigger system is single action, and an enormous number of single action firearms are still produced. That said, they are also very simple to operate for the most part. Single-action guns have to be cocked before every shot, and pretty much all single action guns are hammer-fired. Cock, then fire. Repeat.

Fairly simple, really.

However, there difference between single action revolvers and single action semi-auto pistols. Single-action revolvers have to be manually cocked before every shot. Semi-auto single action pistols, however, can be cocked manually or by the cycling the slide. The latter operation can be achieved by charging the pistol (racking the slide) or after a shot is fired, so these pistols at most will only need to be cocked once.

    For the concealed carrier, single action handguns impose certain concessions. The pistol has to be carried in one of the following manners:
  • Pistol loaded, hammer down Sometimes called Condition 2, the pistol is charged (meaning loaded and a round chambered) but the hammer has been manually de-cocked. The hammer must be cocked before firing. Revolvers can be carried in this manner, but older handgun designs (meaning pre-1900) lack a drop safety, which is why many people carried with the hammer down over an empty chamber.
  • Cocked and locked. This method of carry is only possible with a single-action semi-auto, such as a Browning Hi Power or 1911 pistol or other single-action pistol with a manual safety. The pistol is loaded, a round is chambered, the hammer is back but the manual safety is engaged. To fire, the safety has to be deactivated.
  • Condition Three or Israeli carry. Also possible only with a semi-auto, this is where a magazine is inserted but the pistol is not charged. To fire, the gun must be drawn, charged, then fired.

While it may seem that the single action system poses disadvantages, it remains popular enough for almost every major handgun maker to still make at least one single action firearm.

Double Action Only

double action gun

Double action only, or DAO, is a double-action pistol without the option for single action operation. Revolvers or semi-autos are available in this configuration.

DAO pistols usually have an internal hammer. There are several reasons for this, firstly being that an exposed hammer is unnecessary since the pistol cannot be manually cocked. Secondly, DAO pistols are popular as concealed carry pistols and enclosing the hammer streamlines the pistol for easier concealment and drawing from concealment.

DAO pistols cock and fire the pistol with every shot, so the trigger pull is usually stiff (8 pounds or more) but can be tamed with aftermarket trigger springs.

These pistols are very simple to use - load and pull the trigger to fire. The long, hard trigger pull guards against accidental discharge.

While DAO pistols can be revolvers or semi-autos, revolvers are most popular. Commons examples include certain models of the J-frame revolver series by Smith and Wesson, Ruger's LCR, certain Charter Arms snubbies and so on. Popular DAO semi-autos include Kahr pistols (which are only offered in DAO) and the Smith and Wesson SDVE series.

Double Action/Single Action

single action gun

Double action/single action, also called DA/SA, is a firing system where both double action and single action operation is possible. Both revolvers and semi-autos are offered in this configuration.

Pistols with this firing and trigger system are almost always hammer-fired, though there are some exceptions like the Walther P99 and the Canik TP9, essentially a P99 derivative. These guns are striker-fired (more on that later) but have double-action and single-action capabilities. However, the standard DA/SA pistol is hammer-operated.

DA/SA revolvers couldn't be simpler. Load, then either fire double-action by pulling the trigger or cock and fire in single action mode. Then repeat. Double action autos, on the other hand, can be slightly more complicated. The semi-auto DA/SA pistol is placed in single action mode when loaded and charged, so the pistol has to be decocked for a double-action shot to be made.

DA/SA guns have a long, stiff double-action trigger pull (usually 10 to 15 pounds of pressure are required to fire) which cocks and fires the pistol or a short, crisp single-action pull (4 to 6 pounds) to fire with a cocked hammer. For the latter, the pistol must be cocked manually in the case of revolvers or decocked semi-autos, or by racking the slide or firing a semi-auto pistol. Semi-auto pistols, when carried loaded in double action mode, will go into single action mode after the first shot.

Some DA/SA semi-autos have a manual safety, enabling cocked-and-locked carry in single action mode but can be carried in double action mode if manually decocked, such as CZ pistols and CZ clones. Some feature a manual safety that also decocks the pistol when engaged, like Beretta or Heckler and Koch pistols; this mechanism allows the user to carry in double action mode with the safety on if desired. Some have a decocking lever only, such as many Sig Sauer pistols, which allow the user to put the gun in double action mode after cocking...but no manual safety can be engaged.

Double action guns, when carried in double action mode, are less prone to accidental discharge, due to the long, hard trigger pull. However, some shooters find the long, stiff double-action pull is not to their linking or impacts their accuracy. This can, however, be overcome with practice.

Additionally, the manual safety/safety-cum-decocker/decocking lever operating procedures can be more complicated than some shooters prefer.

Striker-Fired Pistols: All The Rage These Days

striker fired gun

Today, the dominant firing mechanism and trigger system is the striker-fired pistol. Popular models are made by numerous manufacturers, though Glock is far and away the best-known and most popular. Striker-fired pistols are only semi-auto, since striker-fired revolvers aren't generally made.

A striker-fired pistol is fairly simple, in that a spring-tensioned striking rod strikes the pistol primer and discharges the round instead of the firing pin or a hammer. However, in striker-fired pistols, the striker is part of the firing pin, whereas the firing pin in other pistols is a single piece.

When the handgun is charged and loaded, the striker is half-cocked. Pulling the trigger fully cocks and discharges the pistol. The cycling of the slide half-cocks the striker again.

Trigger pull is light, usually 4 to 7 pounds. Operation is simple - insert magazine, rack the slide, start shooting. For concealed carry, that means you're able to begin shooting as soon as you can get the gun out of the holster.

However, these pistols have to be carried in a holster that fully protects the trigger guard. Accidental discharges have been documented where a striker pistol was fired when a piece of clothing or something else got into the holster and was able to operate the trigger.

Choosing The Single Action, Double Action, SA/DA or Striker Fire Pistols

pistol firing mechanisms to choose from single or double action

Which firing mechanism and trigger operation is right for you is something that you'll have to find for yourself; some people swear by single action, some by double action and others insist that striker pistols are the pinnacle of handgun design. Each has their benefits and drawbacks, as you have read above.

To find what would be best, consider what sort of safety measures you want for a carry gun. Some believe the fewer the better, some want a few redundancies.

If at all possible, try to rent a few pistols from a range that has guns available for rent. You should be able to get a feel for what works best for you.

Sam Hoober
 

About The Author

Born in southeastern Washington State, Sam Hoober graduated in 2011 from Eastern Washington University. He resides in the great Inland Northwest, with his wife and child. His varied interests and hobbies include camping, fishing, hunting, and spending time at the gun range as often as possible.