Excerpt from this Guide:
1959: Colt acquires manufacturing and marketing rights
to AR15.
1962: Colt gets US Department of Defense orders 85,000 M16’s for Vietnam
and 19,000 for the Air Force.
Mid 60’s: The M16A1 was updated with a new buffer to
reduce the rate of fire, chrome plated chamber and barrel, closed prong
flash hider, forward bolt assist, new buttstock with cleaning kit, and a
30 shot magazine. Rifles were also produced by GM and Harington &
Richardson during the Vietnam war as well as outside the USA.
1978: M16A2 was produced using an increase barrel
diameter, rifling was changed from 1:12 to 1:7 to accommodate a new 62
gr. bullet, modified rear sight, case deflector, new round handguard,
and full-auto was replaced with three round burst.
1994: M4 was adopted based on a demand for a shorter
lightweight weapon. The M4 has a 14.5” barrel and a four position
telescoping stock. Collapsed length is under 30 inches and weighs just
over 5 1/2 pounds. Effective range is 600 yards. Available in 3 shot
burst or full-auto. M4’s are also equipped with a Picatinny -Weaver Rail
System to replace the carry handle.
