View Full Version : Single And Double Action?

August 28, 2007, 10:37 PM
I am going to buy my first semi-auto pistol and I don't understand the single action and double action. Will someone explain in simple words what is the difference and why do some pistol have both.
Thanks in advance.

August 28, 2007, 10:52 PM
Double action only, as you pull the trigger it pulls the hammer back and then releases. When the slide recoils it does not cock the hammer so every shot is the same double action.
DA/SA will fire as a double action but when the slide recoils from the first shot it also cocks the hammer. Therefor much lighter trigger pull for the following shots. All you are doing with the trigger pull then is to release the hammer. Personally, I prefer the DA/SA. You can safely carry with one in the chamber so you don't have to rack the slide to be ready and still fire fairly quickly as double action. Single action firing is usually easier to hold on target while rapid firing, at least for me.

August 28, 2007, 10:59 PM
single action = you just shoot the perp .

double action = you shoot the perp AND his lawyer

August 29, 2007, 07:11 AM
double action = you shoot the perp AND his lawyer

Priceless. I am dying over here.

August 29, 2007, 11:35 AM
The simplest explanation is related to what happens when you pull the trigger.
On a single action, pulling the trigger fires the gun. The hammer must be cocked for each shot.
On a double action, pulling the trigger cocks and fires the gun.

There are several different ways to achieve it, but the best illustration is a DA revolver:
If you simply pull the trigger, you can see the hammer being cocked and then released. Also, you can cock the hammer manually which makes it a single action.

That concept applies to semi-autos as well.
The 1911 is a single action auto. In order for the pistol to fire, the hammer must be cocked (and safeties disengaged). The cycling of the action loads the next round and cocks the hammer. So, this is considered single action only.
On a double action auto, you will usually find a decocking lever. The purpose of the decocker is to allow you to lower the hammer on a loaded chamber. Remember that when you load the pistol and chamber a round, the hammer will be cocked. Decocking it safely lowers the hammer on the loaded chamber. Once the hammer is lowered, your first shot is double-action (refer to the revolver example above). Each subsequent shot is single action. Most DA autos do not have a manual safety. Some refer to these as DA/SA autos.

There are also Double Action Only pistols and revolvers. In these examples, there is no option to manually cock the hammer and fire single action. DAO autos fire double action for every shot. Most DAO pistols do not have manual safeties.

The advantage of single action only pistols and revolvers is the trigger pull. Single actions have a much lighter trigger and much less travel (usually). That is one of the main reasons behind the popularity of the 1911.
Some people mistakenly believe that DA autos are safer. I believe it was Cooper or Taylor who said that double action autos were a solution in search of a problem. SA autos can require a higher level of proficiency than DA autos. Many people don't feel comfortable carrying a pistol with the hammer cocked. They are under some delusion that it is somehow less safe. Some argue that having to disengage the manual safety before firing requires more training.
The only advantage I can see in a DA auto is that most have no mechanical safety. Like a DA revolver, you simply grab the gun and pull the trigger. The disadvantages are primarily in the weight and length of the trigger pull. DA/SA autos also have two different trigger pulls: the first long and heavy one and the lighter one for each subsequent (SA) shot. DAO pistols have the same trigger pull every shot, but they still do not have as light a trigger as a SA nor as short travel.