| Trigger (mechanism) |
Article Index for Trigger |
Website Links For Trigger |
Information AboutTrigger (mechanism) |
|
. Within the looping Trigger Guard is the finger operated trigger.]] A trigger is a mechanism that actuates the firing of a weapon. Firearms , spear guns and crossbows generally have a finger operated trigger. FUNCTION Firearms utilize triggers to initiate the firing of a cartridge in the firing chamber of the weapon. This is accomplished by actuating a striking device through a combination of spring and kinetic energy operating through a firing pin to strike and ignite the primer. There are two primary types of striking mechanisms, hammers and strikers. Hammers are spring-tensioned masses of metal that pivot on a pin when released and strike a firing pin to discharge a cartridge. Strikers are, essentially, spring-loaded firing pins that travel on an axis in-line with the cartridge eliminating the need for a separate hammer. The connection between the trigger and the hammer is generally referred to as the sear surface. Variable mechanisms will have this surface directly on the trigger and hammer or have separate sears or other connecting parts. MECHANISMS There are numerous types of trigger mechanisms. They are categorized according to which functions the trigger is to perform. In addition to releasing the hammer or the striker, a trigger may cock the hammer or striker, rotate a revolver's cylinder, deactivate passive safeties, select between semi-automatic and full-automatic fire ( Steyr AUG ), or pre-set a 'set trigger.' Most modern firearms utilize the trigger to deactivate passive safeties but this does not change how they are identified. Single action (SA) A single-action trigger performs the single action of releasing the hammer or striker. Examples of the SA trigger operated firearms are the Colt Peacemaker revolver, Colt M1911 pistol, and Mauser 98 rifle. Double action (DA) Invented by Robert Adams , a double-action trigger performs the two functions of cocking and then releasing the hammer or striker. This term is applied only to revolvers and the trigger also rotates the cylinder. Though this is technically a third action, it is correct to refer to the mechanism as double-action. More confusingly, revolvers with a double-action trigger mechanism almost always retain the single action functionality. The hammer may be cocked and the trigger pulled. A typical DA revolver is the Smith and Wesson model 19 revolver. Double action only (DAO) Double action only is similar to a DA revolver trigger mechanism however there is no single action function. For semi-automatic pistols with a traditional hammer, the hammer will return to its decocked position after each shot. For striker-fired pistols such as the Taurus 24/7 , the striker will remain in the rest position through the entire reloading cycle. This term applies mostly to semi-automatic handguns, however the term can also apply to some revolvers such as the Smith and Wesson Centennial revolver. Double action/single action (DA/SA) A double action/single action firearm combines the features of both mechanisms. Often called '''traditional double action,''' these terms apply only to semi-automatic handguns. The function of this trigger mechanism is identical to a DA revolver, however the firing mechanism automatically cocks the hammer or striker after the gun is fired. This mechanism will cock and release the hammer when the hammer is in the down position but on each subsequent shot, the trigger will function as a single action. Pre-set Pre-set hammers and strikers apply only to semi-automatic handguns. Upon firing a cartridge or loading the chamber, the hammer or striker will rest in a partially cocked position. The trigger serves the function of completing the cocking cycle and then releasing the striker or hammer. While technically two actions, it differs from a double-action trigger in that the trigger is not capable of fully cocking the striker or hammer. An example of a pre-set striker mechanism is the Glock 17 . An example of a pre-set hammer is the Kel-Tec P-32 pistol. Pre-set hybrid Pre-set hybrid triggers are similar to a DA/SA trigger in reverse. The first pull of the trigger is pre-set. If the striker or hammer fail to discharge the cartirdge, the trigger may be pulled again and will operate as a DAO until a malfunction is cleared or the cartridge discharges. This allows the operator to attempt to fire a cartridge after a misfire malfunction. The Taurus 24/7 Pro pistol (not to be confused with the first-generation 24/4 which was a traditional pre-set) offers this feature as of 2006. RELATIVE MERITS Each trigger mechanism has its own merits. Historically, the first type of trigger was the single action. This is the simplest mechanism and generally the shortest, lightest, and smoothest pull available. The pull is also consistent from shot to shot so no adjustments in technique are need for proper accuracy. Because the hammer must be manually cocked prior to firing, an added level of safety is present and no manual safety is required. Double action triggers provide the ability to fire the gun no matter whether the hammer is cocked or uncocked. This feature is desirable for military, police, or self-defense pistols. The primary disadvantage of any double-action trigger is the extra length the trigger must be pulled and the extra weight required to overcome the spring tension of the hammer or striker. DAO firearms attempt to solve the problems with DA/SA mechanisms by making each and every shot a double-action shot. Because there is no difference in pull weights, training and practice are simplified. Additionally, accidental discharges are reduced because of the heavier trigger pulls. This is a particular advantage for a police pistol. These weapons also generally lack any type of external safety. DAO is a popular mechanism for police agencies and small, personal protection firearms. The primary deficiency is that accurate fire is difficult due to the additional trigger weight and travel required for each shot. DA/SA pistols are versatile mechanisms. These complex firearms generally have a manual safety that may or may not serve to decock the hammer. Some have a decocking lever and a manual safety as well. As a disadvantage, these levers are often intermingled with other levers such as slide releases and takedown levers with variables that become confusing. Extensive training will largely overcome this weakness. One other disadvantage is the difference between the first double-action pull and subsequent single-action pulls. In the middle of a string of shots, this can cause confusion, unintentional discharges, and inaccuracy. Pre-set triggers, only recently coming into vogue, offer what some would consider an optimum balance of pull weight, trigger travel, safety, and consistency. Glock pioneered this trigger and many other manufacturers have followed suit. The primary disadvantage of the pre-set trigger is that pulling the trigger a second time will not discharge the weapon. In normal handling of the firearm, this is not an issue; loading the gun requires that the slide be retracted, pre-setting the striker. This is only of concern with a certain type of misfire where the primer does not detonate on the first strike. There is some debate over the merits of a lightweight single action or pre-set trigger in defensive firearms. Recently, Glock has been sued with varying success for having triggers that are too easy to manipulate. To their credit, Glock offers concerned agencies a so-called New York Trigger with a pull weight similar to a DAO pistol. |
|
|