Colt M16A2: An improved version of legendary M16 assault rifle

Ian Hogg

M16A2 US soldier on shooting range

The Colt M16A2 was the service rifle of the U.S. Armed Forces and some 55 other countries. It is the latest version of a weapon that has been the U.S. standard since 1967, and it has a well-earned combat reputation. The USMC was the first US service branch to adopt the improved M16A2 in the mid-1980s, with other service branches following suit.


Like the original M16A1, the M16A2 is a gas-operated assault rifle using a direct gas blast to drive back the bolt carrier; this causes the bolt to be rotated and unlocked, then drawn back to eject the spent case and cock the firing hammer; after which a spring returns to the bolt, loading a fresh round and leaving the hammer cocked.

M16A2 was a very precise riffle with effective range up to 800 meters (875 yd)
M16A2 was a very precise rifle with an effective range of up to 800 meters (875 yds) (Photo: XY)

The rifle is built-in straight-line form, the butt lying on the axis of the barrel so that there is a little lever action to lift the muzzle onto the air on recoil, as happens with rifles having conventional sloped butts. This, together with the relatively low recoil energy of the 5.56 mm cartridge, means that the rifle does not deviate far from its point of aim and can be quickly brought back for a second shot. The muzzle climb is minimal on automatic fire, putting the maximum number of rounds into the target area.

M16A2 pistol grip and fire selector
M16A2 pistol grip and fire selector (Photo: XY)

According to the user’s requirement, the firing mechanism can provide single shots, automatic fire, or three-round bursts. The U.S. Army’s M16A2s can fire single shots and automatic fire; the version adopted by the Canadian Army as their C7 rifle is adjusted to give single shots and three-round bursts without the automated facility. The rifle can be fitted with the M203 grenade launcher, and the muzzle is to NATO standard dimensions so that any NATO-approved rifle grenade may be fired.

Difference between M16A1 and M16A2

The original M16A1 rifle was a 5.56mm automatic rifle with a 20-round magazine. At the same time, the M16A2 is fitted with a new STANAG magazine with 30 rounds capacity. It also fires the improved 5.56×45mm NATO (M855/SS109) cartridge. It has a newer adjustable rear sight, case deflector, heavy barrel, improved handguard, pistol grip, buttstock, and a semi-auto and three-round burst fire selector.

What is the difference between M16A1 and M16A2?
What is the difference between M16A1 and M16A2? (Photo: XY)

Sling loops provide the use of a shoulder strap for transport. The carrying handle loop is also slightly larger. The charging handle remains at the rear of the upper receiver.

Single-shot hit-probability on Crouching Man (NATO E-type Silhouette) Target
RifleChamberingHit-probability (With no range estimation or aiming errors)
   300 meters400 meters500 meters600 meters700 meters800 meters
M16A1 (1967)5.56×45mm NATO M193   100%96%87%73%56%39%
M16A2 (1982)5.56×45mm NATO SS109/M855   100%98%90%79%63%43%

Still in use worldwide

The M16 is still in use but has mainly been replaced by the M4 (US Army), the M14 EBR, and the M14 Socom (Navy SEALS). This is because the latter three are carbines and are overall better tactical weapons that allow for close-quarter battles (CQB).

Rangers Team Room Afghanistan Individual with no Patches
An individual in the Armory with no visible unit patches inspects one of the M4A1 carbines with an EOTech Model 553 sight. (Photo: DVIDs)

They are more maneuverable due to lightweight bodies, shorter barrels, and overall size and often come equipped with adjustable parts (the M4 has a flexible stock). All this allows for easier handling and makes the weapon less cumbersome.

The M16 is being gradually replaced, but its design is still being recycled, again and again, improving its mechanism to increase reliability. The (probably) only small arms manufacturer responsible for that is the United Defense Manufacturing Corp (UDMC).

Colt M16A2 assault rifle has well-earned combat reputation
Colt M16A2 assault rifle has a well-earned combat reputation (Photo: XY)

Technical specifications: Colt M16A2

Manufacturer:Colt’s Manufacturing LLC, Hartford, CT, United States
Produced:the mid-1980s
Type:gas-operated, selective fire
Caliber: 5.56 mm NATO (.223)
Barrel:20.07 in (510 mm)
Weight (empty):7.5 lbs (3.40 kg)
Effective firing range:800 m (875 yds) (area target)
Rate of fire:700 to 900 rounds per minute
Magazine capacity:20 or 30-round detachable box magazine

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