Colt M4

   Since the early 1970s the Colt Firearms company developed various carbine versions of the AR-15. The Colt Model 720 is essentially a shortened version of the M16A2 assault rifle. It has a shorter barrel and telescopic buttstock. As a result this weapon was much more comfortable to carry and to use. The US Army adopted this carbine in 1994 as the M4. This carbine is still in service and being issued as a personal defense weapon for the non-frontline troops, vehicle drivers, artillery crews, airborne troops and special operation units. The Colt M4 is also in service with at least 30 operators worldwide.

   It is a gas operated, selective fire weapon, chambered for the standard NATO 5.56 x 45 mm ammunition. It's internal design is similar to that of the M16A2. In fact these weapons have 80% parts commonality. Because of the shorter barrel this weapon has an effective range of 360 meters.

   The safety / fire mode selector switch is located on the left side of the receiver, above the pistol grip. Trigger mechanism has semi-auto and three round burst modes. A cocking handle is located at the rear of the receiver and does not reciprocate when the gun is fired. Ejection port is located on the right side. It has a deflector, which propels spent cases away from left-handed shooters.

   This carbine is fed from the standard M16 magazines, holding 30 rounds. This weapon is also compatible with the earlier 20-round magazines of the original M16 and other standard STANAG magazines.

   Standard adjustable iron sights of the M16 are of diopter type. Range adjustments are made by rotating a rear knob. The M4 has a sighting range of 600 meters. Later production models were fitted with a Picatinny-type rail on top of the receiver for attachment of sights. These could also mount a detachable carrying handle.

   The Colt M4 has a telescopic 4-position stock, which is adjusted for length, and allows to shorten the rifle when required. It is worth mentioning that the M16A2 rifles have solid stocks, because of internal design limitations of this weapon, which cannot be adapted for a folding buttstock.

   Basically it is compatible with all accessories, used by  the M16, including a modified M203A1 underbarrel grenade launcher, knife-bayonet, tactical flashlights, laser pointers and silencers.

Variants

   M4A1 carbine. It is similar to the M16A3 assault rifle. This version is fitted with a Picatinny-type rail instead of the carrying handle, which accepts a variety of scopes. A detachable carrying handle can be installed. Weapon's trigger mechanism has a full-auto mode instead of the three shot burst;

   M4 Commando, a compact carbine, fitted with even shorter barrel. It is used in limited numbers by the US Army special operation groups and Marine force recon troops.