An AR-15–style rifle is a lightweight semi-automatic rifle based on or similar to the Colt AR-15 design. The Colt model removed the selective fire feature of its predecessor, the original ArmaLite AR-
Rifles styled like the AR-15 come in many sizes and have many options, depending on the manufacturer. The lower receiver, without the receiver extension, rear takedown pin, and buttstock, is shown at bottom.
1973 Colt AR-15 SP1 rifle with 'slab side' lower receiver (lacking raised boss around magazine release button) and original Colt 20-round box magazine
A stripped lower receiver, one that is lacking the additional parts included in a completed lower receiver, is the only part of an AR-15–style rifle that needs to be transferred through a federally licensed firearms dealer under United States federal law.
American Tactical OMNI AR-15–style rifle (lower in polymer), 5.56×45mm NATO caliber, with Millett DMS-1 scope and FAB Defense stock and grips
The M16 rifle is a family of assault rifles adapted from the ArmaLite AR-15 rifle for the United States military. The original M16 rifle was a 5.56×45mm automatic rifle with a 20-round magazine.
AR-15–style rifle
…predecessor, the original ArmaLite AR-15, which is a scaled-down derivative of the AR-10 design (by Eugene Stoner). It is closely related to the military M16 rifle. ArmaLite sold the patent and trademarks for both to Colt's Manufacturing Company in 1959 after the military rejected the design in favor of the M14…
From top to bottom: M16A1, M16A2, M4A1, M16A4.
A Marine of the 3rd Battalion, 1st Marines cleans his XM16E1 in December 1967.
Front cover – The M16A1 Rifle – Operation and Preventive Maintenance by Will Eisner, issued to American soldiers in 1969 during the Vietnam War