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.
R
RADIAL PRESSURE GAUGE
A British term denoting a Gauge to measure cartridge-developed pressure through the sidewall of a case or shotshell tube as opposed to measuring the pressure transmitted through the head.
RAMP SIGHT
A sight blade and/or base with a rearward-facing sloped surface.
RAMROD
A rod used in seating a load in muzzle loading firearms.
RANGE
1. An area equipped for testing or using firearms and ammunition. 2. An area designated for engaging in shooting sports. 3. The horizontal distance between the firearm and the target.
RATCHET
A notched wheel on the rear of a revolver cylinder which causes the cylinder to rotate when so urged by a lever called a Hand or Pawl.
Also Known As: Hand, Pawl
RATE OF TWIST
The distance required for the rifling to complete one revolution.
REAR SIGHT
Any metallic sight used in conjunction with a metallic front sight located anywhere between the shooter eye and the front sight.
REBARREL
The replacing of a barrel with another barrel.
REBATED CARTRIDGE
A centerfire cartridge case whose rim diameter is smaller than the diameter of the body of the case at the head.
Also Known As: Rebated Case, Rebated Head
REBOUND LEVER
A rotating device designed to move the hammer into a position in which there is no contact of either hammer and firing pin or firing pin and primer. It may also be used to position a safety device between the hammer and firing pin or primer.
REBOUND SLIDE
A reciprocating device found in some double action revolvers which moves the hammer into a position in which there is no contact of either hammer and firing pin or firing pin and primer. It can also be used to position a safety device between hammer and firing pin or primer in such revolvers.
Also Known As: Rebound
REBOUNDING HAMMER
A feature of some firearms, wherein the hammer, after striking the firing pin, retracts slightly away from the firing pin before coming to rest.
REBOUNDING LOCK
A type of firing mechanism, wherein the hammer or striker after forward movement retracts slightly to a rest position.
RECEIVER
The basic unit of a firearm which houses the firing and breech mechanism and to which the barrel and stock are assembled. In revolvers, pistols, and break-open guns, it is called the Frame.
Also Known As: Frame
RECEIVER BRIDGE
That part of the receiver on bolt action rifles that arches over the rear of the bolt hole. If cut to allow the passage of the bolt handle it is known as a Split Bridge.
Also Known As: Split Bridge
RECEIVER RING
The front part of the receiver on bolt action rifles into which the barrel is fitted.
RECEIVER SIGHT
Any rear sight fitted to the receiver of a firearm, but usually refers to an aperture or “peep” sight.
Also Known As: Peep Sight, Aperture Sight
RECESSED BOLT
A bolt with a counterbore in the forward end to accommodate the head of the cartridge case.
RECHAMBER
The cutting of a new chamber in a barrel to accommodate a cartridge of the same bore diameter.
RECOIL
The rearward movement of a firearm resulting from firing a cartridge or shotshell. Sometimes informally called “Kick”.
Also Known As: Kick
RECOIL ABSORBER
Any device that reduces the perceived recoil of a firearm.
RECOIL LUG
A block or plate on the bottom of a receiver and/or barrel to transfer the recoil to the stock.
Also Known As: Recoil Shoulder
RECOIL OPERATED ACTION
A self-loading type firearm in which the force of recoil is used to unlock the breech bolt and then to complete the cycle of extracting, ejecting and reloading.
Also Known As: Recoil Operated
RECOIL PAD
A butt plate, usually of rubber, to reduce the sensible recoil of shoulder firearms.
RECOIL PENDULUM
A device for measuring Free Recoil Energy in which a firearm is suspended from fixed points so as to allow it to swing freely while the barrel remains horizontal.
RECOIL PLATE
Steel insert in the frame of a revolver immediately surrounding the firing pin hole; also called Firing Pin Bushing.
Also Known As: Firing Pin Bushing, Bolster Face
Related Terms: RECOIL LUG
RECOIL SHIELD
On a revolver, a lateral extension of the standing breech, to each side, to prevent fired or unfired cartridges from coming out of the chambers and to protect the otherwise exposed primers of unfired cartridges.
RECOIL SPRING
A spring used to store some recoil energy and subsequently close the action and feed the next round in semiautomatic firearms. In other designs, a recoil spring may serve to absorb recoil energy or perform other functions.
Also Known As: Counter Recoil Spring, Operating Spring, Closing Spring, Retracting Spring
REDUCED CHARGE
A less than nominal powder charge.
REFERENCE AMMUNITION
Ammunition used to qualify and/or calibrate velocity and pressure measuring systems.
REGULATING BARRELS
The adjusting of the relationship of the axes of multi-barreled firearms so as to make the points of impact coincide at a given distance.
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.
RELIEF ENGRAVING
The carving of raised scenes that produces three-dimensional figures.
RELOADING
The process of reassembling a fired cartridge case with a new primer, propellant and bullet or wads and shot. Also called Handloading when performed manually. See Handloading.
Related Terms: HANDLOADING
RELOADING COMPONENTS
Cartridge cases (new or used), primers, propellant powder, bullets, or shot and wads, used in handloading ammunition.
RELOADING DATA
A description of recommended relationships of reloading components.
RELOADING DIES
Tools which hold and/or reform cartridge cases or shotshells during a reloading operation.
RELOADING POWDER
Propellant made available to consumers for handloading ammunition. Also called Canister Powders.
Also Known As: Canister Powder
RELOADING PRESS
A mechanical device for hand-loading metallic cartridges or shotshells.
REMAINING VELOCITY
Velocity that a projectile retains at any specific location along its trajectory path.
REPEATER
Any firearm equipped with a magazine that holds more than one shot without reloading.
REPEATING FIREARM
A firearm utilizing a reservoir of ammunition, typically a magazine or a revolving cylinder, capable of holding a quantity of cartridges and an action that makes possible firing of successive shots until the reservoir is depleted.
Related Terms: ACTION, CYLINDER, MAGAZINE
RESIDUAL PRESSURE
The pressure level that remains in the cartridge case or the shell within the firearm’s chamber, and in the bore, the moment the projectile leaves the muzzle of the firearm.
REST
A device to support a firearm during firing.
RESTOCK
The replacement of one stock with another.
RETICLE
The aiming reference seen when looking through a telescopic sight.
RETRACTOR
Part used to move a breech bolt to rear.
REVOLVER
A firearm, usually a handgun, with a cylinder having several chambers so arranged as to rotate around an axis and be discharged successively by the same firing mechanism through a common barrel.
RIB
A raised surface used as a sighting plane. Ribs may be either solid or ventilated. See Ventilated Rib.
Related Terms: VENTILATED RIB
RIB EXTENSION
The protrusion of a rib beyond the breech end of a barrel.
RICOCHET
The glancing rebound of a projectile after impact.
RIFLE
A firearm having helical features in the bore to impart spin to a single projectile and designed to be fired from the shoulder.
RIFLED SLUG
A projectile with helical features and a hollow base, intended for use in smoothbore shotguns.
RIFLING
Any type of helical internal bore feature of the barrel wall that imparts spin on the projectile for the purpose of stabilizing it in flight. This may be a series of lands and grooves, polygonal, hexagonal, or other configurations.
RIFLING BROACH
A tool having a series of cutting edges of progressively increasing height used to cut the helical features in a rifled barrel.
RIFLING HEAD
That part of the hook or cut rifling tooling that holds the cutter and the mechanism for deepening the cut as the operation progresses.
RIFLING PITCH
The distance the projectile must move along a rifled bore to make one revolution. Usually expressed as “one turn in x inches (or millimeters).”
Also Known As: Twist Rate
RIM
The flanged portion of the head of a rimfire cartridge, certain types of centerfire rifle and revolver cartridges and shotshells. The flanged portion is usually larger in diameter than the cartridge or shotshell body diameter and provides a projecting lip for the firearm extractor to Engauge so that the cartridge or shotshell may be extracted from the chamber after firing. In a rimfire cartridge the rim provides a cavity into which the priming mixture is charged.
RIM SEAT
A counterbore in the rear end of a chamber or bolt face to support the head of a rimmed cartridge.
RIMFIRE CARTRIDGE
A rimmed cartridge design in which the rim is formed with a cavity to contain the priming mix.
RIMFIRE PRIMER
A type of primer found in the circumferential cavity or rim of rimfire ammunition. Usable only with rimfire guns. See Centerfire Primer.
Related Terms: CENTERFIRE PRIMER
RIMLESS CASE
A centerfire cartridge whose case head is of the same diameter as the body and having a groove turned forward of the head to provide the extraction surface.
Also Known As: Rimless Cartridge
RIMMED CASE
A cartridge having a rimmed or flanged head that is larger in diameter than the body of the case. May be either rimfire or centerfire.
Also Known As: Rimmed Cartridge
RING BULGE
A circumferential bulge in a barrel typically caused by firing into an obstructed bore. See also Bulged Barrel.
Also Known As: Ringed Barrel
Related Terms: BULGED BARREL
RIVELLING
A British term for the wrinkled appearance of some shotgun bores.
ROLL CRIMP
A method of securing a bullet into a metallic cartridge case by bending the case mouth inward. See Taper Crimp.
ROLLED CRIMP
A method of closing the mouth of a shotshell by inverting the mouth of the tube upon itself over a top wad or slug. See Folded Crimp.
ROLLING BLOCK ACTION
A single shot action in which a breech block and hammer rotate about separate transverse pins in the receiver. The two members are swung rearward, away from the barrel breech to load the chamber or extract a cartridge case. To fire a cartridge, the breech block is closed and locking is accomplished by the falling hammer engaging an abutment under the breech block.
Also Known As: Rolling Block
ROTARY MAGAZINE
A form of magazine in which the cartridges are arranged about a central rotating spindle or carrier. See Mannlicher Magazine.
Also Known As: Spool Magazine
Related Terms: MANNLICHER MAGAZINE
ROUND
One complete small arms cartridge.
ROUND BALL PROJECTILE
A spherical projectile, usually of lead or lead alloy.
ROUND BUTT
A design of a handgun backstrap in which the lower portion features a rounded profile.
ROUND NOSE BULLET
An elongated projectile with a radiused nose.
RUPTURE
A generally circumferential separation in the side wall of a cartridge case. May be complete or partial.
Also Known As: Case Head Separation, Case Separation, Case Rupture