As defined in 'The guide
book for Marines"
18 revised edition:
The M16A2 rifle is a 5.56X45mm, magazine-fed,
gas-operated,
air-cooled, shoulder-fired weapon. It is designed for either semiautomatic or three-round burst-control
fire through the use of a selector lever. The barrel is surrounded by two aluminum lined fiberglass hand guards which are notched to permit
air to circulate around the barrel and further serve to protect the
gas tube. A super nylon
butt plate is attached to the rear of the stock to partially reduce the effects of recoil. A forward assist assembly located on the right rear of the upper reciever permits manual locking of the bolt when this is not done by the force of the action spring. A spring-loaded rataining pin can be
depressed with the nose of a cartridge to allow the trigger guard to be rotated down against the pistol
grip to permit the firer ready access to the trigger when wearing gloves. A dust cover is provided to prevent dirt and
sand from getting into the rifle through the ejection port. The dust cover should be kept closed at all times when the rifle is not being fired. It is opened automatically by the forward or rearward movment of the bolt carrier.
General data:
weight without magazine: 7.78 lbs
with 32 rd
mag fully loaded: 8.79 lbs
length overall with flash compensator 21 inches.
standard ammunition includes ball, tracer and blank