In a firearm, the sear is the part of the trigger mechanism that holds the hammer, striker, or bolt back until the correct amount of pressure has been applied to the trigger, at which point the hammer, striker, or bolt is released to discharge the weapon. The sear may be a separate part or can be a surface incorporated into the trigger. Sear mechanisms are also frequently employed in archery release aids.
As one firearms manufacturer notes:
Sear: A sharp bar, resting in a notch (or in British: "bent") in a hammer (or in British: "tumbler"), holding the hammer back under the tension of the mainspring. When the trigger is pulled, the sear moves out of its notch, releasing the hammer and firing the gun. [1]
The term "sear" is sometimes incorrectly used to describe a complete trigger group.
Within a trigger group, any number of sears may exist. For example, a Ruger Blackhawk single-action revolver contains one for releasing the hammer. A Ruger Redhawk double/single-action revolver contains two, one for single-action release and the other for double-action release. A Browning BLR rifle contains three sears, all used simultaneously for hammer release. On many select-fire weapons, two sears exist, one for semi-automatic fire and the second for full-automatic fire. In this case, the selector switch disengages one over the other.
Trigger sears are a key component for trigger pull characteristics. Larger sears create creep while shorter ones produce a crisp pull. Aftermarket trigger companies, such as Bold, Timney, and Jewell, produce products in which sear contact is adjustable for personal preference. When a gunsmith does a "trigger job" to improve the quality and release of a trigger pull, most often the work includes modifying the sear, such as polishing, lapping, etc.
The sear on many firearms is often connected to a disconnector, which, after a cycle of semi-automatic fire has proceeded, keeps the hammer in place until the trigger is released and the sear takes over. Many firearms, such as the M1911 pistol, use a notch in the slide of the handgun that the top end of the disconnector returns to after the trigger is released. When the trigger is still under pressure by the firearm operator, the disconnector will not retract to its resting position. On other handguns, such as the Series 80 version of the M1911, a firing pin block acts as an internal safety, which is disengaged by the disconnector after the trigger is pulled. However, because of the spring tension placed on the disconnector by the firing pin block, the weight of the trigger pull is significantly increased.
Trigger pull is related to the interaction of the sear with the trigger and the spring. It can be measured, regulated and adjusted, but it is a complicated mechanical problem. [2]
The sear has been found on early weapons such as the crossbow. [3] The term may be related to the French verb serrer, "to grip", and the noun serre, "claw, talon, grasp." [4] The term appears in Hamlet : "the Clown shall make those laugh whose lungs are tickled o'th' sear" (i.e. those who have a 'hair-trigger' laugh reaction). [5] [6] [4] [7]
A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and used by an individual. The term is legally defined further in different countries.
A revolver is a repeating handgun that has at least one barrel and uses a revolving cylinder containing multiple chambers for firing. Because most revolver models hold up to six cartridges, before needing to be reloaded, revolvers are commonly called six shooters.
In firearms terminology, an action is the functional mechanism of a breech-loading firearm that handles the ammunition cartridges, or the method by which that mechanism works. Actions are technically not present on muzzleloaders, as all those are single-shot firearms with a closed off breech with the powder and projectile manually loaded from the muzzle. Instead, the muzzleloader ignition mechanism is referred to as the lock.
A semi-automatic firearm, also called a self-loading or autoloading firearm, is a repeating firearm whose action mechanism automatically loads a following round of cartridge into the chamber and prepares it for subsequent firing, but requires the shooter to manually actuate the trigger in order to discharge each shot. Typically, this involves the weapon's action utilizing the excess energy released during the preceding shot to unlock and move the bolt, extracting and ejecting the spent cartridge case from the chamber, re-cocking the firing mechanism, and loading a new cartridge into the firing chamber, all without input from the user. To fire again, however, the user must actively release the trigger, allow it to "reset", before pulling the trigger again to fire off the next round. As a result, each trigger pull only discharges a single round from a semi-automatic weapon, as opposed to a fully automatic weapon, which will shoot continuously as long as the ammunition is replete and the trigger is kept depressed.
A semi-automatic pistol is a handgun that automatically ejects and loads cartridges in its chamber after every shot fired. Only one round of ammunition is fired each time the trigger is pulled, as the pistol's fire control group disconnects the trigger mechanism from the firing pin/striker until the trigger has been released and reset.
A firing pin or striker is a part of the firing mechanism of a firearm that impacts the primer in the base of a cartridge and causes it to fire. In firearms terminology, a striker is a particular type of firing pin where a compressed spring acts directly on the firing pin to provide the impact force rather than it being struck by a hammer.
Pump action is a type of manual firearm action that is operated by moving a sliding handguard on the gun's forestock. When shooting, the sliding forend is pulled rearward to eject any expended cartridge and typically to cock the hammer or striker, and then pushed forward to load a new cartridge into the chamber. Most pump-action firearms use an integral tubular magazine, although some do use detachable box magazines. Pump-action firearms are typically associated with shotguns, although it has been used in rifles, grenade launchers, as well as other types of firearms. A firearm using this operating mechanism is colloquially referred to as a pumpgun.
A firearm is said to fire from an open bolt if, when ready to fire, the bolt and working parts are held to the rear of the receiver, with no round in the chamber. When the trigger is actuated, the bolt travels forward, feeds a cartridge from the magazine or belt into the chamber, and fires that cartridge in the same movement. Like any other self-loading design, the action is cycled by the energy released from the propellant, which sends the bolt back to the rear, compressing the mainspring in readiness for firing the next round. In an open-bolt gun firing semi-automatically, the bolt is caught and held at this point by the sear after each shot; and in automatic open-bolt fire, it's caught and held in this manner whenever the trigger is released. In contrast to this, in closed-bolt guns, the trigger and sear do not affect the movement of the bolt directly.
The lock of a firearm is the mechanism used to initiate firing. It is a historical term, in that it generally refers to such mechanisms used in muzzle-loading and early breech-loading firearms. Side-lock refers to the type of construction, in which the individual components of the mechanism are mounted either side of a single plate. The assembly is then mounted to the stock on the side of the firearm. In modern firearm designs, the mechanism to initiate firing is generally constructed within the frame or receiver of the firearm and is referred to as the firing or trigger mechanism.
A trigger is a mechanism that actuates the function of a ranged weapon such as a firearm, airgun, crossbow, or speargun. The word may also be used to describe a switch that initiates the operation of other non-shooting devices such as a trap, a power tool, or a quick release. A small amount of energy applied to the trigger leads to the release of much more energy.
The hammer is a part of a firearm that is used to strike the percussion cap/primer, or a separate firing pin, to ignite the propellant and fire the projectile. It is so called due to the fact that it resembles a hammer in both form and function. The hammer itself is a metal piece that forcefully rotates about a pivot point.
A handgun is a firearm designed to be usable with only one hand. It is distinguished from a long gun which needs to be held by both hands and braced against the shoulder. Handguns have shorter effective ranges compared to long guns, and are much harder to shoot accurately. While most early handguns are single-shot pistols, the two most common types of handguns used in modern times are revolvers and semi-automatic pistols, although other handguns such as derringers and machine pistols also see infrequent usage.
A pistol is a type of handgun, characterized by a barrel with an integral chamber. The word "pistol" is derived from the Middle French pistolet, meaning a small gun or knife, and first appeared in the English language c. 1570 when early handguns were produced in Europe. In colloquial usage, the word "pistol" is often used as a generic term to describe any type of handgun, inclusive of revolvers and the pocket-sized derringers.
The following are terms related to firearms and ammunition topics.
The Ruger SR-Series is a line of semi-automatic pistols manufactured by Sturm, Ruger & Company. At 1.18 in (30.0 mm) thick through the grip, it is touted by Ruger as one of the thinnest double-stack pistols available. The SR-series has been marketed as a backup/concealment weapon for law enforcement as well as for civilian concealed carry. The Ruger SR9 chambered for the 9×19mm Parabellum cartridge was introduced in October 2007, and the slightly smaller SR9c came out in January 2010. The Ruger SR40 chambered for the .40 S&W cartridge came out in October 2010, and the compact SR40c in June 2011.
Muzzle rise, muzzle flip or muzzle climb refers to the tendency of a firearm's or airgun's muzzle to rise up after firing. It more specifically refers to the seemingly unpredictable "jump" of the firearm's muzzle, caused by combined recoil from multiple shots being fired in quick succession. It has an adverse effect on maintaining accuracy with using automatic weapons or rapid-firing semi-automatic firearms, as a moving muzzle can throw off the shooter's aim, causing subsequent shots to miss the intended target.
In firearms, a safety or safety catch is a mechanism used to help prevent the accidental discharge of a firearm, helping to ensure safer handling.
The Walther PPX and the Walther Creed semi-automatic pistols were developed by the German company Carl Walther GmbH Sportwaffen of Ulm as low-cost duty handguns. The PPX was available in 9×19mm Parabellum and .40 S&W. Its successor, the Creed, was available only in 9mm.
A repeating firearm or repeater is any firearm that is capable of being fired repeatedly before having to be manually reloaded with new ammunition into the firearm.