In a

firearm A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see Legal definitions). The first firearms originated in 10th-century China, when bamboo tubes ...

, 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 aid In archery, a release aid, mechanical release, or release is a device that helps to fire arrows more precisely, by using a trigger to release the bowstring, rather than the archer's fingers. It is used to make the release of the bowstring quicker ...

Description

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.

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 A revolver (also called a wheel gun) is a repeating firearm, repeating handgun that has at least one gun barrel, barrel and uses a revolving cylinder (firearms), cylinder containing multiple chamber (firearms), chambers (each holding a single ...

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 A rifle is a long-barreled firearm designed for accurate shooting, with a barrel that has a helical pattern of grooves ( rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with ...

contains three sears, all used simultaneously for hammer release. On many

select-fire Selective fire is the capability of a weapon to be adjusted to fire in semi-automatic, fully automatic, and/or burst mode. The modes are chosen by means of a selector switch, which varies depending on the weapon's design. Some selective-fire w ...

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 Polishing is the process of creating a smooth and shiny surface by rubbing it or by applying a chemical treatment, leaving a clean surface with a significant specular reflection (still limited by the index of refraction of the material accordin ...

lapping Lapping is a machining process in which two surfaces are rubbed together with an abrasive between them, by hand movement or using a machine. Lapping often follows other subtractive processes with more aggressive material removal as a first ste ...

, 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.

History

The sear has been found on early weapons such as the

crossbow A crossbow is a ranged weapon using an Elasticity (physics), elastic launching device consisting of a Bow and arrow, bow-like assembly called a ''prod'', mounted horizontally on a main frame called a ''tiller'', which is hand-held in a similar ...

. The term may be related to the French verb ''serrer'', "to grip", and the noun ''serre'', "claw, talon, grasp." The term appears in ''

Hamlet ''The Tragedy of Hamlet, Prince of Denmark'', often shortened to ''Hamlet'' (), is a tragedy written by William Shakespeare sometime between 1599 and 1601. It is Shakespeare's longest play, with 29,551 words. Set in Denmark, the play depicts ...

'': "the Clown shall make those laugh whose lungs are tickled o'th' sear" (i.e. those who have a ' hair-trigger' laugh reaction).

Notes

Bibliography

* ''Guns'' by Dudley Pope, 1969, Hamlyn Publishing Group, Ltd.

External links

Animation of a M1911 firing sequence
{{DEFAULTSORT:Sear (Firearm) Firearm components