The Glossary of Industry terms has been compiled by SAAMI’s Technical Committee to facilitate technical interchanges between members of that committee. It is not intended to provide legal definitions of the terms included, and, in light of further experience, the definitions of these terms may change. It is not intended to be comprehensive since it does not cover the full range of the diversity of the sporting arms and ammunition industry’s products. It is, in other words, a working draft that, it is hoped, may be useful in addressing certain technical matters frequently considered by the Technical Committee and is subject to further change and refinement.
It was the committee’s decision that ONLY industry terms would be included which are unique to the firearms and ammunition industry directly. Optical terms have been omitted for the most part. Common metallurgical terms were not included because they are not unique to the industry. Where there is a common term with a usage unique to our industry, it has, however, been included.
Search Results for: trigger
ACTUATOR
Part of the firing mechanism in certain automatic firearms, such as trigger actuator, which slides forward and back in preparing each round to be fired.
ADJUSTABLE TRIGGER
Any trigger mechanism which has features that can be adjusted.
AUTOMATIC ACTION
A firearm design that continuously feeds cartridges, fires and ejects cartridge cases as long as the trigger is fully depressed and there are cartridges available in the feed system. Actuation of the mechanism may be from an internal power source such as gas pressure or recoil, or external power source, such as electricity.
Also Known As: Auto, Full Auto, Machine Gun
AUTOMATIC RIFLE
A fully automatic shoulder firearm that starts firing when the trigger is pulled and continues until the trigger is released or ammunition is exhausted. The term should not be used in conjunction with semiautomatic firearms. See Semiautomatic.
Also Known As: Automatic Fire
Related Terms: SEMIAUTOMATIC
BENT
A notch, usually in the hammer, in which the sear or trigger is held under tension of the mainspring until released by movement of the trigger or hammer. See Half Cock. See Full Cock.
Related Terms: FULL-COCK, HALF COCK
CRISP TRIGGER
A trigger that releases without sensible movement.
CROSS BOLT SAFETY
A type of manual firearm safety operated by a lateral force on a button usually located in the trigger guard. Also called Push-Button Safety.
Also Known As: Push Button Safety
DISCONNECTOR
A device intended to disengage the sear from the trigger. 1.) In a manually operated firearm, it is intended to prevent firing without pulling the trigger. 2.) In a semiautomatic firearm, it is intended to prevent full automatic firing. 3. A device that prevents out-of-battery firing.
DOUBLE ACTION
A firing mechanism in which the trigger serves the dual purpose of cocking and then releasing the firing mechanism – either hammer or striker. Double action firearms can be manually cocked similar to single action mode. For differentiation, see Single Action and Double Action Only.
DOUBLE ACTION ONLY
A firing mechanism in which the trigger serves the dual purpose of cocking and then releasing the firing mechanism – either hammer or striker. Double action only (DAO) firearms cannot be manually cocked to emulate single action mode. For differentiation, see Single Action and Double Action.
DOUBLE ACTION PISTOL
A pistol mechanism in which a single pull of the trigger cocks and releases the hammer.
DOUBLE ACTION REVOLVER
A type of revolver in which the rotation of the cylinder, cocking and firing are performed by a single pull of the trigger. Most Double Action revolvers can also be fired in the single action mode by manually cocking the hammer.
DOUBLE PULL TRIGGER (2 STAGE)
A trigger which has two distinctive pull characteristics. The first or take-up stage is usually long and light in pull force; the second stage having a short but distinct increase in the pull force required to discharge the firearm.
DOUBLE SET TRIGGER
An arrangement of two triggers in which the actuation of one trigger presets the second resulting in a light trigger pull of the latter.
DOUBLE TRIGGER
A term used for firearms having two barrels and a separate trigger for the discharge of each. This term does not apply to firearms with double set triggers.
DOUBLING
Simultaneous discharge of both barrels of a double-gun with a single pull of the trigger.
FAIL-TO-FIRE
A failure of the firearm to discharge after the trigger has been pulled. It can be one of two types: 1.) a complete misfire, or 2.) a delayed fire.
FIRE CONTROL
The mechanism that utilizes trigger action to release the energy to initiate the primer. It may include but not lmited to the trigger, hammer, sear, disconnector, and/or safety.
Also Known As: Fire Control System
GRIP
1. In handguns, the handle. 2. In shoulder arms, that portion of the stock to the rear of the trigger.
GUARD SCREW
A screw that extends from the trigger guard into and through the stock.
HAIR TRIGGER
A slang term for a trigger requiring very low force to actuate. Sometimes used to describe the light pull of a second trigger in a double set trigger mechanism.
HALF COCK
The position of the hammer, when about half retracted and held by the sear, intended to prevent release of the hammer by a normal pull of the trigger. This can be the safety or loading position of many guns.
HALF COCK SAFETY
The position of the hammer, when about half retracted and held by the sear, intended to prevent release of the hammer by a normal pull of the trigger. This can be the safety or loading position of many guns.
Also Known As: Half Cock
HAMMER BLOCK
A device intended to isolate the hammer from the firing pin except when the trigger is pulled.
HAMMER STRUT
A component part of some firing mechanisms which is connected between the hammer and the trigger and which acts to move the hammer to the firing position when the trigger is pulled. Also refers to a strut which guides a mainspring to power a hammer.
Also Known As: Strut
HINGED OR FOLDING TRIGGER
A trigger which is hinged to fold forward.
INERTIA TRIGGER
The term used for firearms having two barrels and a single trigger wherein the inertia resulting from the recoil forces of firing one barrel causes the trigger sear to switch to the unfired barrel. A second pull of the trigger can then fire the second barrel.
KNURL, KNURLING
1. A series of regular ridges or rectangles on a metal surface to help prevent slipping. Used on triggers, hammers, bolt handles, etc. 2. Sometimes used in referring to cartridge case or bullet cannelures.
NON-SELECTIVE SINGLE
A single trigger on double-barrel guns which fires the barrels in a fixed sequence.
OPEN BREECH ACTION
An action in which the breech bolt is held open until the trigger is pulled.
Also Known As: Open Bolt Action
OVERTRAVEL
The distance after a particular event occurs in the normal operation of the firearm, e.g. additional rearward motion of the trigger after sear or hammer release.
PISTOL GRIP
On shoulder firearms, that part of the stock behind the trigger, shaped similar to the grip of a pistol to afford a better grasp.
PISTOL GRIP STOCK
A stock or buttstock having a downward extension behind the trigger guard somewhat resembling the grip of a pistol.
PRETRAVEL
The initial distance the trigger moves prior to sear movement. Also known as Trigger Take-up or Slack. See Trigger Creep.
Also Known As: Trigger-Take Up, Trigger Slack
Related Terms: TRIGGER CREEP
RELEASE TRIGGER
An unconventional mechanism generally found only in some trap shotguns in which the firearm is fired by the release of, rather than the pull of, the trigger.
SELECTIVE SINGLE TRIGGER
An arrangement on double-barrel firearms having a single trigger which enables the shooter to choose the barrel he wishes to fire first. The mechanism will then subsequently switch to the unfired barrel, which a second pull of the trigger can then fire.
SELECTOR
1. In a double barreled gun, a device to allow the shooter to choose which barrel is to be fired by the first pull of the trigger. 2. A lever which enables the shooter to choose the type of fire, semi-auto or full auto, with high or low rate of automatic fire.
SELF-LOADER
An action in which each pull of the trigger results in a complete firing cycle from discharge through reloading. It is necessary that the trigger be released and pulled for each firing cycle. Also called Autoloader or Self-Loader. For Blowback Operated: See Blowback Action. See Delayed Blowback Action. For Recoil Operated: See Recoil Operated Action. For Gas Operated Action: See Gas Operated Action. For Inertia Operated: See Inertia Operated Action
Also Known As: Semiautomatic
Related Terms: BLOWBACK ACTION, DELAYED BLOWBACK ACTION, GAS OPERATED ACTION, INERTIA OPERATED ACTION, RECOIL OPERATED ACTION
SEMIAUTOMATIC
Firearm which fires, extracts, ejects and reloads once for each pull and release of the trigger. Also called Self-loading or Auto-loading.
Also Known As: Self-Loader, Self-Loading, Auto-Loading
SEMIAUTOMATIC ACTION
A self-loading, magazine-fed firearm in which each pull of the trigger results in a complete firing cycle from firing through loading. It is necessary that the trigger be released and pulled for each firing cycle. See
Also Known As: Semiautomatic, Auto-Loader
Related Terms: SELF-LOADER
SERRATED TRIGGER
A trigger having longitudinal grooves on its face.
SET TRIGGER
Either a single or double trigger arrangement on which the required trigger pull force can be made very light by means of “setting” mechanism. May be either Double Set trigger or Single Set trigger.
SETTING
The arming of a set-trigger mechanism of a firearm so equipped. See Set Trigger.
Related Terms: SET TRIGGER
SHEATH TRIGGER
A trigger which has a minimum projection from the action and is not usually surrounded by a trigger guard. Also called Spur Trigger.
Also Known As: Spur Trigger
SHOE
1. A metallic adapter fastened to a trigger to widen the surface. 2. A metallic insert in the forearm of a side-by-side double barreled shotgun by which the forearm is attached to the barrels. Also called Fore-end Iron, Fore-end Plate.
Also Known As: Fore-End Iron, Fore-End Plate
SIDE LOCK ACTION
An action in which the fire control system is attached to a side plate rather than being integral with the frame or trigger plate.
Also Known As: Action Bar Lock
SINGLE ACTION
A firing mechanism in which the trigger serves the sole purpose of releasing the firing mechanism – either hammer or striker. For differentiation: See Double Action. See Double Action Only.
Related Terms: DOUBLE ACTION, DOUBLE ACTION ONLY
SINGLE ACTION PISTOL
A pistol mechanism which requires the manual cocking of the hammer or striker before pressure on the trigger releases the firing mechanism.
SINGLE ACTION REVOLVER
A type of revolver in which the hammer must be cocked manually to rotate the cylinder for each shot. The firearm is then discharged by a pull of the trigger. The process is repeated for each shot.
SINGLE STAGE TRIGGER
1. A trigger mechanism in which the trigger travel is relatively short and there is no significant sensible change in pull force from the beginning of movement up to the point of firing. 2. A trigger which releases with a single pull.
SINGLE TRIGGER
A trigger mechanism for multiple barrel firearms wherein repeated pulls of one trigger fires the barrels successively.
SINGLE-DOUBLE TRIGGER
A type of trigger mechanism found on some double-barrel or over-under shotguns consisting of two triggers. The front trigger functions as a conventional non-selective single trigger, while the rear trigger will fire only the barrel with the tighter choke.
STIRRUP
A component with divided legs to apply force equally. Mainly used in a trigger assembly where it is necessary to straddle another component.
STOCK DIMENSIONS
General stock dimensions consist of the following: length of pull, drop at comb, drop at Monte Carlo, drop at heel, pitch and cast.
A. Rifles 1. Cast is the lateral displacement of the centerline of the buttplate (pad) from the centerline of the bore. For a right-handed shooter, when the centerline of the buttplate is to the left of the bore, it is expressed as cast-on and to the right as cast-off. The opposite is true for left-handed shooters. 2. Drop is the vertical distance from the line of sight to the comb, Monte Carlo or heel of the stock. It is measured from an extension of a straight line drawn from the top of the front sight through the top surface of the open rear sight adjacent to the notch. The drops for target rifles are usually measured from the centerline of the bore. 3. Girth – The smallest circumferential dimension at the pistol grip. 4. Length of Pull – The distance from the center of the trigger to the center of the buttplate or recoil pad. 5. Length of Stock – The greatest dimension of the stock material. 6. Pitch – Not usually given for rifle.
B. Shotguns 1. Cast – Same as A.1., above. 2. Drop is the vertical distance from the line of sight to the comb, Monte Carlo or heel of the stock. It is measured from an extension of a straight line drawn from the base of the front bead sight across the highest point on the frame or receiver. 3. Girth – Same as A.3., above. 4. Length of Pull – same as A.4., above. 5. Length of Stock – Same as A.5., above. 6. Pitch is an expression used to indicate the relationship of the bore to the plane of the buttplate (pad). It is found by extending a line across the butt and drawing at right angles to this line an additional line through the highest point on the receiver or frame and measuring the distance from an extension of this line to a point at the base of the front sight bead. The pitch is said to be if the described line is above the front sight and if below. The pitch is normally down.
Also Known As: Drop at Comb, Drop at Heel, Drop at Monte Carlo, Cast
STOCKMAKER'S HAND SCREWS
Extra long screws used by stockmakers during the inletting operation to maintain alignment of the trigger guard and other auxiliary items with the action. Also known as Inletting Screws or Guide Screws.
Also Known As: Inletting Screws, Guide Screws
STUD TRIGGER
A button-type trigger, the end of which is pressed to fire the firearm.
TANG SCREW
The screw or screws passing through either one or both tangs by which the stock or trigger guard is attached to the receiver or frame.
TARGET TRIGGER
1. A trigger mechanism which provides for adjustment of such characteristics as pull force, travel or overtravel. 2. A trigger which provides a large bearing surface for the trigger finger. 3. A relatively light, crisp trigger designed to assist in accurate shooting.
THUMB REST
A ledge in the grip area of a rifle or handgun on which to rest the thumb of the trigger hand.
THUMB SAFETY
A type of manual safety in which the external control component is located for convenient operation by the thumb of the trigger hand.
THUMBHOLE STOCK
Any stock having a contoured hole in the grip area to accommodate the thumb of the trigger hand.
TRIGGER
That part of a firearm mechanism which is moved manually to cause the firearm to discharge.
TRIGGER BAR
A connecting piece between the trigger and the sear.
TRIGGER CREEP
The sensible movement of the trigger or take-up or pretravel, prior to sear release.
Also Known As: Creep
TRIGGER GUARD
A rigid loop which partially surrounds the trigger to reduce the possibility of accidental discharge.
TRIGGER LOCK
1. An accessory for blocking unauthorized trigger movement during gun storage. Must never be applied to a loaded firearm. 2. A form of firearm safety blocking trigger movement.
TRIGGER MECHANISM
Those parts which, when pressure is applied to the trigger, release the hammer or striker. Also called Fire Control.
Also Known As: Fire Control
TRIGGER PLATE (ASSEMBLY)
1. A metal plate fitted to the lower part of some frames through which the trigger or triggers pass. 2. A component attached to the frame or receiver of some firearms, which supports the major components of the firing mechanism and may have the trigger guard as an integral portion.
TRIGGER PULL FORCE
The peak force which must be applied to the trigger of a firearm, approximately parallel to the bore line, to cause the sear, striker, or hammer to release.
TRIGGER PULL SCALE
A device for measuring trigger release force.
TRIGGER SHOE
An accessory which is attached to the trigger to give a much larger trigger-finger bearing surface.
TRIGGER SQUEEZE
A gradual increase of pressure on a trigger until it releases.
TRIGGER STOP
1. A device to prevent certain firearms from being fired until the finger lever is closed. 2. A device to prevent over-travel of the trigger.
TRIP
A part of the mechanism of some firearms which is released by the action of the trigger.
TWIN-SINGLE TRIGGER
A double trigger arrangement used on some double-barrel firearms, wherein one or both triggers will, with each pull, fire the barrels sequentially. They are non-selective.
UNDER-LEVER ACTION
The same as a top break mechanism except that the lever that unlocks the firearm, allowing the barrels to pivot and expose the breech, is located below the trigger guard or forms the trigger guard.
WUNDHAMMER SWELL (BULGE)
A bulge or swelling in the pistol grip of a stock to fit the palm of the trigger hand. Named after inventor Louis Wundhammer.