Any discussion about handgun actions and triggers is not as simple as just listing a few universally-accepted types and describing their evident characteristics. I am sad to say this and don’t want to make this more complex than it is, especially for new shooters, but there are several key factors in gun actions to think about that may have life-altering consequences. The “action” of a handgun refers to the mechanical relationships between the trigger and the hammer. No matter what action, the trigger’s most basic function is to release the hammer or striker. But depending on the action type, the trigger may cock the hammer/striker, deactivate passive safeties, rotate the revolver’s cylinder, and complete several other functions. Pressing the trigger with some actions may both cock and release the hammer, while with others only one result occurs. All types have advantages and disadvantages. There are strong opinions about all trigger actions, so do your own research for your own personal decision. What type of action do you want in your handgun? Why?
Several shooters don’t even think about their trigger type or action when purchasing or using their handgun nor when defining what they want up front when buying one. Consider: What are the common types of handgun triggers and which one[s] is[are] best for you and your purpose[s]? How do you compare one type of trigger or action to another? What are the characteristics of each trigger type and action? Can you be more accurate with one type of trigger over another? Can you fire one trigger/action type faster than another to help you confront bad guys/gals and for multiple attackers? Now these questions are not meant to be frightening or scare you as a new shooter or someone concerned about self defense. But there are many trigger and action factors at play when shooting which directly affect shot placement, follow-up shots, the amount of force required for the shot, movement, and outcomes. Trigger control is one of the most crucial shooting fundamentals and I believe THE most important one, although several are very important. You must know your gun’s trigger and action and how to properly manipulate and control it; familiarity and practice are paramount. You should know that some shooters even disagree on the trigger mechanisms, features, pros and cons, and benefits. The basic information that follows about trigger actions is meant to be introductory for new shooters and a refresher review for experienced shooters, based on my very basic understanding. Certainly, be open to what others believe about trigger types and benefits, do your own research, and then try it before you make your own decisions. Each type has its own merits. This information is meant to help you understand the type and characteristics of the trigger you have on your present gun and to help you when generally operating it and purchasing future guns.
There are 5 common types of trigger mechanisms or actions on handguns. I will refer to them as types of triggers. It is important to know the type of action for your handgun because it involves whether or not a hammer must be cocked for the gun to first fire, whether a firing pin or striker bar operates, how many actions must occur for the gun to fire, whether or not the gun is only cocked by trigger manipulation, what trigger press weight is necessary for the gun to fire, whether the slide must be cycled to cock the gun, and other things. So you see that the type of trigger affects you the shooter in many ways, the least of which is not your quick follow-up shots, the amount of movement, and the necessary force to press the trigger for accuracy to defend your life. While the definition of the various actions can be specified, as I mentioned there is disagreement and debate about the type of actions that some guns have and their operations. But, here are my 5 trigger actions.
Common Trigger Action Types
The 5 common trigger actions or types are:
1) Single Action Only (SAO);
2) Double Action (DA);
3) Double Action Only (DAO);
4) Double Action/Single Action (DA/SA); and
5) Striker-Fired or Partially Cocked Striker (SF).
Single Action Only (SAO)
A SAO trigger performs the single (only) action of releasing the hammer or striker to fire the gun each time the trigger is pressed. If the hammer is not cocked on a SAO gun like a 1911, pressing the trigger will result in no shot being fired. Generally, the SAO is the simplest action and the shortest, lightest, and smoothest press. The press is also consistent from shot to shot, so minimal adjustments in technique are needed for proper accuracy. A major advantage of most SAO pistols is that, when cocked, the firing mechanism can be released and fired with a very short press of the trigger, usually less than 1/4″, as well as a soft press (near 4 pounds or so.) Less movement from exerting less force on the trigger usually means a more accurate shot. On a SAO pistol, the hammer will be cocked and the gun ready to fire by chambering a round, so often an external safety is used. Many prefer to carry a SAO “cocked and locked” with a round in the chamber and the safety on. Proper training and practice are important for this carry technique and new shooters should be very cautious and deliberate in this decision. Examples of the SAO pistol include the Colt 1911 Government Model, the Browning P-35 Hi-Power, the German P-08 Luger, the Springfield 1911 EMP, the Sig 238, Beretta Neos, Ruger Mark III, and the Russian Tokarev TT33. Many early firearms of single action design are revolvers (like the Colt Single-Action Army [Peacemaker]-introduced in1873-think Buffalo Bill Cody, Theodore Roosevelt & Gen. George Patton), but some semi-automatic pistols, such as the Colt 1911, must be manually cocked before the first round may be fired and is automatically cocked for successive shots, are also SAO. Almost all rifles and shotguns use this type of trigger. For SAO pistols then, to chamber the first round you rack the slide and then the movement of the slide ejects the empty case and automatically chambers the next round, after firing. While SAO pistols require that the hammer or striker be cocked before the first round can be fired, most designs cock the hammer or striker as part of the loading process (i.e. the act of inserting the magazine and operating the slide to chamber the first round also cocks the hammer or striker into the ready-to-fire position.) Again, once the first round is fired, the automatic slide movement (recoil) cocks the hammer or striker for each subsequent shot. Then once cocked, the pistol can be fired by pulling the trigger once for each shot until the magazine is empty.
An Ongoing Debate: Note that some say that striker-fired (SF) guns are really SAO, as they are fully cocked by the manual cyclng of the slide or other operation. Others disagree and believe that SF guns are not SAO and are DAO. In actuality, there are different types of SF guns and they are pseudo-SAO or pseudo-DAO in nature. There are some SF guns that are more SAO, like the Springfield Armory XD with no hammer and fires when you press the trigger. (Some debate this still.) Then there are Glock SF guns which are more like pseudo-DAO with a pre-set, partially-cocked function. What sets these apart from DAO guns is that the cycling of the slide partially cocks the striker with its built-in spring-loaded firing pin and then the pulling of the trigger then finishes cocking the striker bar and releases it to strike the primer and ignite the cartridge to make the gun go bang. Keep in mind the above SAO definition that requires the trigger to be pressed to perform only one action, the release of the hammer or striker to make the gun go bang. In a pure SF system, such as with all Glocks, Smith & Wesson M&Ps, Springfield XDs, and Ruger SR9s and SR9Cs, there is no external hammer and no means to de-cock the gun. They are cocked by racking the slide and the usual way to de-cock is to press the trigger. There are even some pseudo DA-SA SF guns, like the S&W SW99 pistol. I believe that technically speaking that SF guns are neither purely DAO nor purely SAO guns, but in their own category of SF. Some SF guns are single action (e.g. my Springfield XD-9 Mod 2), since racking the slide cocks the striker and then the trigger releases it to fire. Other SF guns are double action (or double-action-only), since racking the slide has no effect on the action and the trigger will cock and release the striker. Many striker-fired guns are sort of a hybrid between single and double-action. In those, the slide does part of the work of cocking the striker, but the trigger then completes the cocking action and then releases the striker to fire the gun (e.g. Glock 17 and 19). In those guns, both slide action and trigger action are required to fire the gun. Note that the International Defensive Pistol Association (IDPA) has debated the SF issue for some time. The 2015 IDPA Rule Book, Section 188.8.131.52, specifies that DA, DAO, and SF semi-automatic firearms now compete in SSP, CCP, or BUG divisions with SAO guns competing in a separate division, like in ESP, CDP, depending upon size and cartridge used, etc. Previously with IDPA, the Springfield XDm was categorized as SAO. Two examples of single action, SF guns are the HKP7 family and the Springfield XD (includes XDm) line.
Click next for Double Action triggers.