Short answer: AR stands for ArmaLite Rifle, after ArmaLite, the company that designed the AR-10 and AR-15 in the 1950s. It does not stand for "assault rifle" or "automatic rifle". A civilian AR-15 is semi-automatic: one shot for each pull of the trigger. A gun that fires more than one shot per trigger pull is a machine gun under federal law, and civilians generally cannot own one made after the federal ban took effect.
Where the AR name came from
- 1954: ArmaLite is founded by the Fairchild Engine Corporation. The company says it is "best known for the development of the 'AR' or 'ArmaLite Rifle' platform".
- 1955: ArmaLite designs the AR-10, its larger rifle; see AR-10 vs AR-15 parts.
- 1959 to 1961: Colt takes over the AR-15. The NRA National Firearms Museum dates the deal to December 1959; Colt's own timeline says it bought exclusive manufacturing and marketing rights in 1961.
- 1963: Colt wins its first government contract, for 104,000 M16 rifles.
Today "AR-15" is used for the whole family of rifles built on the same design, from many makers. For how it differs from the military carbine, see AR-15 vs M4.
AR does not mean "assault rifle"
"AR" is a company name. What matters legally is how the rifle fires. Federal law defines a machine gun as any weapon that shoots "automatically more than one shot, without manual reloading, by a single function of the trigger", and makes it unlawful to transfer or possess one, except for government use or one lawfully possessed before that law took effect. A civilian AR-15 fires once per trigger pull, so it is not a machine gun. Some states use the term "assault weapon" for rifles with certain features; that is a separate idea, covered in our featureless AR-15 guide.
Other "AR" names
- AR-10: ArmaLite's larger rifle, usually .308.
- AR-15: the 5.56/.223 rifle Colt took over.
- AR-9: a common name for 9mm AR-pattern carbines; see our AR-9 guide.
- AR pistol: an AR-15 built as a pistol; see how to build an AR pistol.
Want to build one? Start with our ultimate AR-15 guide and the AR-15 builder, and compare lower receivers by price.
Sources: ArmaLite, the NRA National Firearms Museum, Colt's timeline, and 26 U.S.C. 5845 and 18 U.S.C. 922(o), read October 2026.
Frequently asked questions
What does AR stand for in guns?
ArmaLite Rifle, after ArmaLite, the company that designed the AR-10 and AR-15 in the 1950s.
Does AR stand for assault rifle?
No. It is the ArmaLite company name. A civilian AR-15 is semi-automatic, one shot per trigger pull.
Does AR stand for automatic rifle?
No. A rifle that fires more than one shot per trigger pull is a machine gun under federal law; a civilian AR-15 is not.
Who makes the AR-15?
ArmaLite designed it and Colt bought the rights between 1959 and 1961. Today many companies make AR-15-pattern rifles and parts.
What is the difference between an AR-15 and an M16?
The M16 is the military rifle Colt supplied from 1963; it can fire automatically. The civilian AR-15 is semi-automatic. See AR-15 vs M4.
What does the 15 in AR-15 mean?
It is ArmaLite's model number; the earlier AR-10 was its larger rifle.
