Like any other subject, the world of firearms has its own terminology which can be confusing to newcomers

Here is a list of some of the common gun terms and acronyms that you will see in print, on websites, or hear in classes and on the sales floor.

NRA National Rifle Association – an organization you should join to support our right to own firearms.  You can sign up on this website or in the store.
NRA-ILA The Institute for Legislative Action is the lobbying arm of the National rifle association.
ISRA Illinois State Rifle Association – They help preserve our gun rights at the state level.  You can join in the store.  ISRA has a range near Kankakee IL.
ISP Illinois State Police – issues FOID (Firearm Owners Identification Card) cards and CCL (Concealed Carry Licenses)
IDPA International Defensive Pistol Association – runs competition events.
USPSA United States Practical Shooting Association – runs competition events.
IPSC International Practical Shooting Confederation – runs competition events.
SASS Single Action Shooting Society – governs cowboy action shooting competition.
SAMMI Sporting Arms and Ammunition Manufacturers Institute – an accredited standards developer.
NSSF National Shooting Sports Foundation – preserves hunting and shooting sports.
AE Angle Eject – used by Winchester on some lever action rifles to denote that they do not eject straight up.
AR As in AR-15, AR stands for Armalite Rifle, not Assault Rifle.  Only Armalite and Colt can use the AR designation, others have to change it to avoid trademark violations – example, Rock River uses LAR.
BAR Browning Automatic Rifle.  Used for the military rifle and the Browning semi-auto civilian hunting rifles.
Bore The inside of the firearm’s barrel.
Bore Sight To align the sights by sighting through the bore.  When mounting a scope, it will get you close so it takes less time to sight in the rifle.
Chamber The part of the firearm that contains the cartridge at firing.
Choke In shotguns, the taper in the last few inches of the barrel.  The bore is tightened to a smaller diameter to keep the shot pattern tighter.  Typical chokes are: Cylinder (no taper), improved cylinder, modified, and full.
Clip Commonly used in place of Magazine, a clip is a strip of metal that holds the ammo for loading into (usually) an internal magazine.
DA Double action – on the trigger pull, the hammer is cocked and then released in one full travel of the trigger
SA Single action – the hammer is cocked by hand before pulling the trigger. This results in a smoother, lighter trigger pull and increases accuracy.
DA/SA A firearm that can be fired either double or single action – can be revolver or semi-auto.
DAO Double action only – mostly used on semi-auto pistols, but there are DAO revolvers.
SAO Single action only – “Cowboy” style revolvers and some semi-auto pistols.
Hammer The device that strikes the firing pin, on some older revolvers the firing pin is on the hammer.
Trigger The device that releases the hammer.
Firing pin The device that strikes the primer, firing the round.
Magazine A device to hold ammunition.  It can be detachable or internal.
Rifling Rifling is a series of spiral lands and groves in the bore that spin the bullet to stabilize it in flight.
Striker In some semi-auto pistols there is no hammer.  This is used in many modern pistols, i.e Glock, S&W, Ruger, etc.  Striker operated pistols can be DAO or SAO. Example: Glock is DAO. The striker is 70% cocked until the trigger is pulled.  The H&K VP series is single action resulting in a lighter, smoother trigger pull.
FA Full Auto – A firearm that continues to fire while the trigger is held back. Machine Gun.
Semi-Auto Semi automatic, or Self Loader.  Each trigger pull fires a round and the gun cycles to load another round into the chamber.
Suppressor Commonly called a silencer or can, it reduces the noise when a gun fires. Not legal in Illinois.
ACP Automatic Colt Pistol
BMG Browning Machine Gun, i.e. 50 BMG is the .50 machine gun.
Cal (Caliber) Bullet diameter, can be in inches or metric.  Example – .357 cal is .357 inches in diameter; 9mm is the metric designation.
Cartridge The complete assembly of a round of ammo, the case, bullet, powder, and primer.
Chambering The term used to describe the round a gun is designed to fire – “This rifle is available in the following chamberings…, i.e. .30-06 Springfield, .223 Remington, etc.”
FPS Feet per Second – the speed of the bullet in flight.
Muzzle Velocity The velocity of the bullet as it leaves the muzzle.
Terminal Velocity The velocity of the bullet at the target.
Muzzle Energy The kinetic energy in foot-pounds of the bullet as it leaves the muzzle – the faster and heavier the bullet = higher energy.
Terminal Ballistics The study of how a bullet behaves when it strikes the target.
Bullet type: HP Hollow point – a bullet designed for controlled expansion as it penetrates the target.
Bullet type: JHP Jacketed hollow point – a bullet with a copper jacket. Most personal defense bullets are this type.
Bullet type: JFP Jacked flat point.
Bullet type: FP Flat point.
Bullet type: Wadcutter Designed to leave a clean hole in a paper target; used for competition.  Used in revolvers, the bullet is flush with the case.
Bullet type: SWC Semi-wadcutter – a bullet designed to work in semi-auto pistols for target shooting.
Bullet type: RN Round nose.
Bullet type: LRN Lead round nose.
Magnum Ammunition with high energy used for hunting.
+P or +P+ Plus Pressure. The difference is +P rounds are dimensionally the same as the parent round, i.e. .39 Spl / .38 Spl +P.  Do not use these rounds in any firearm that is not marked for +P, however can be used in guns that accept Magnum rounds.
WMR Winchester Magnum Rimfire, also known as .22 Magnum.  Cannot be used in .22 LR chambered guns.
9mm Parabellum The 9 x 19mm round used by NATO countries, police, and civilian target shooters. Also called 9mm Luger because it was developed by Georg Luger.
GC Gas Check; a copper-zinc cup used on the base of a lead bullet to protect the base from hot gasses.  It keeps down distortion and seals the bore so there is less blow-by increasing velocity.
Grain A unit of measurement used for bullets and powder. One pound = 7000 grains, abrev. gr as in 115 gr RN bullet.
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