Colt M16 automatic rifle / light machine gun / light support weapon (USA)

Picture 1: Colt M16A1 automatic rifle / light machine gun

Picture 2: Colt M16A2 automatic rifle / light machine gun with 100-round Beta-C magazine

Picture 3: Colt M16A3 automatic rifle / light machine gun. Note detachable carrying handle, installed over the integral Picatinny rail, and relocated bipod

Picture 4: Colt M16A3 automatic rifle / light machine gun

Data for current production Colt M16 automatic rifle / LMG

Caliber	5.56x45 NATO
Weight	5.78 kg
Length	1000 mm
Barrel length	510 mm
Feed	magazine, 30 or 100 rounds
Rate of fire	600 - 750 rounds per minute

Colt company build a variety of heavy barreled “automatic rifles” (machine rifles, light machine guns) based on most versions of the M16 assault rifle, starting from early XM16E1 (which also unsuccessfully were converted to belt feed) and up to latest M16A4 assault rifles. These weapons were sold abroad, and a small number of such rifles were used by US Marine Corps in the Squad Automatic weapon role during late 1970s and 1980s, before adoption of the M249 light machine gun. It is worth to note that current production Colt M16 LMG are produced in Canada rather than USA, by Colt Canada factory (former Diemaco Ltd).

Colt M16 automatic rifle is gas operated, air cooled, magazine fed weapon which fires from open bolt. Gas system is copied from M16 rifle, and is of direct-impingement type, as there is no dedicated gas piston, and powder gases are fed from the gas block via gas tube into the bolt carrier. Rotary bolt has seven locking lugs and locks into the barrel extension. Receiver is made from aluminum alloy and consists of two parts, upper and lower, which are linked by two cross-pins. Barrel is of heavy profile and cannot be replaced in the field. Gun is fitted with hydraulic recoil buffer (located in the buttstock) which decreases the rate of fire.
Feed is from magazines only; any M16-compatible magazine can be used, but most common are either 100-round double-drum magazines, made by American company Beta-C Co, or standard issue 30-round curved box magazines for M16 rifle.

Standard furniture includes large plastic handguard of rectangular cross-section, with attached vertical fore-grip and mounting point for detachable, folding bipod. Rifles of most recent production also feature detachable M16A4-style carrying handle with built-in fully adjustable rear sight; this handle can be attached to the Picatinny type rail on the top of the receiver. Alternatively, any other sighting equipment can be installed on this rail using appropriate mountings.