The
M16 rifle, officially designated
Rifle, Caliber 5.56 mm, M16, is a United States military adaptation of the ArmaLite
AR-15 rifle.
[8][9][10][n 1] The original M16 was a
select-fire,
5.56×45mm rifle with a 20-round magazine.
The AR-15 rifle was first built in 1958 by
ArmaLite as a
selective fire weapon for military purposes. Since then, it has been produced in many different versions. The term "AR-15" signifies "Armalite rifle, design 15".
[11] Colt uses the label "AR-15" for the
semiautomatic civilian models it produced after selling the rifle to the U.S. military as the
M16 rifle, and so many use this term only for civilian models. This article discusses the original design for military users and its major variants, however they are labelled.