List of Colt AR-15 and M16 rifle variants

Colt has been the most visible producer of ArmaLite AR-15 pattern weapons, and the military designations M16 and M4 are heavily associated with the company. Colt has an intricate internal nomenclature system for its models, with a variety of suffixes and prefixes. Colt's systems have generally followed the times and though its model numbers originally came without prefixes, with the need to separate weapons made for civilian consumption from those made for military and law enforcement use, military models became prefixed with the code "R0". For the purposes of this table, the R0 nomenclature is obviated as this terminology did not exist in all cases, but it can be understood to be present. Military/LE models are also easily identified by their three-digit code in contrast to the four-digit codes for civilian weapons. Colt Armalite AR-15 The original Armalite AR-15 models have the charging handle located on top of the upper receiver, protected within the carrying handle. Colt M16 Rifle, M4 Carbine based weapons Colt military models without model numbers In rare instances some Colt models have been produced without in house model numbers, or at least one which is readily apparent. Diemaco/Colt Canada models The Canadian company Colt Canada (formerly Diemaco) licensed production of a rifle (Colt Model 715) and carbine (Colt Model 725), but later went on to produce an entire line of AR-15/M16 pattern weapons developed independently. In May 2005, Colt's Manufacturing Company acquired Diemaco, and the name was changed to Colt Canada. Non-factory military models ==Colt civilian models==

Colt's civilian line of semi-automatic Colt AR-15 rifles is identified by a four digit code following a specific prefix. Initially all Colt civilian weapons were listed with an “R” prefix, with this changing to “AR” following the passage of the Federal Assault Weapons Ban in 1994. Colt also produced a line of weapons aimed at target shooters under the “MT” prefix, which stood for Match Target, as well as, the Colt Accurized Rifle, which was the only model to feature the CR prefix. Most recently with the shift in marketing policy by Colt Defense, these weapons have been given the “LE” and "LT" prefix. The "LT" series is modified version of the Colt 6720 featuring a lightweight "pencil" barrel with a free floating rail system. Only 1500 of the "LT" series were produced. Currently, Colt Defense has no line targeted specifically at the private civilian market. R series models AR series models MT and CR series models LE series models LT series models CE series models ==Glossary of terms==

Stock Fixed Stocks • A1: Fixed stock as used on M16 and M16A1. May or may not have a trapdoor to store a cleaning kit • A2: Improved stock used on M16A2. Longer by 5/8" • Tubular: Fixed tubular buttstock, similar to the 2nd Generation retractable unit, using a receiver extension and triangular rear with buttplate Retractable Stocks • 1st Generation: 2-position sliding stock that resembled a shortened fixed buttstock • 2nd Generation: 2-position aluminum retractable stock • 3rd Generation: 2-position fiberlite retractable stock. Introduced 1985 • Canadian 3rd Generation: 4-position fiberlite retractable stock fitted with rubber buttpad • 4th Generation: 4-position nylon retractable stock. Introduced 2002, designed by Picatinny Arsenal engineer Lily Ko with reinforced ribs, an angled buttplate, and a rear sling swivel • Retractable ACR: Similar in design to the so-called "Crane Stock" (initially fabricated by the Naval Surface Warfare Center Crane Division) essentially a 3rd generation unit with integrated cheek-rest • FPW Wire: Retractable wire stock similar in appearance to the stock used on the M3 submachine gun • Israeli: Rebuilt 3rd Generation stocks with 6 positions instead of 2 Handguards • Triangular: Triangular rifle handguards • Short Triangular: Carbine length triangular handguards • Round: Smooth round rifle handguards • Short Round: Carbine length smooth round handguard • Ribbed: Ribbed round rifle handguards • Short Ribbed: Carbine length ribbed handguards • Square LMG: Special heavy handguards with integral vertical grip for use during sustained fire • FF Tube: Free-Float Tube • M4: Oval carbine handguards with double heatshields • Rail/RIS: Handguards are replaced with a Rail Integration System. • Monolithic Rail Platform (MRP): A variant Rail System made by LMT. It has a free-floating barrel for greater accuracy. • ACR Type: Advanced Combat Rifle Project Handguard Fire control • S-1: The selector is Safe (S) – Semi-Automatic (1) • S-F: The selector is Safe (S) – Fully Automatic (F) • S-1-F: The selector is Safe (S) – Semi-Automatic (1) – Fully Automatic (F) • S-1–3: The selector is Safe (S) – Semi-Automatic (1) – 3-Round Burst (3) • S-F-1–3: The selector is Safe (S) – Fully Automatic (F) – Semi-Automatic (1) – 3-Round Burst (3). First Generation 4 position group • S-1–3-F: The selector is Safe (S) – Semi-Automatic (1) – 3-Round Burst (3) – Fully Automatic (F). Second Generation 4 position group Rear sight • A1: "Field sights" in which the rear sight is only adjustable for windage • A2: Rear sight adjustable for both windage and elevation • Flattop: Indicates carry handle and rear sight has been replaced with a MIL-STD-1913 rail. A detachable carry handle can be attached to the rail which features either A1 (Diemaco/Colt Canada) or A2 (Colt) sights • Weaver: Indicates carry handle and rear sight has been replaced with a Weaver-type rail. A detachable carry handle can be attached to the rail which features either A1 (Diemaco/Colt Canada) or A2 (Colt) sights Barrel profile • ArmaLite Early ArmaLite AR-15 ultra-lightweight 'Hollywood' turned-down profile barrel, 1:14 twist only • A1: Also referred to as the "lightweight" or "pencil" profile. Government-specified barrel profile increased to between 0.675 and 0.575 inches • A2: Also referred to as the "government" or "gov't" profile. Barrel profile for which the portion of the barrel in front of handguards is thickened to 0.715 inches • HBAR: A barrel that in some portion is thicker than government-profile, usually underneath the handguards • M4: Government barrel profile with small portion reduced to 0.575 inches to mount M203 grenade launcher • M4 HBAR: M4 barrel with portion under handguard thickened for sustained automatic fire • Super Heavy: Special Colt bull target/match barrel • SFW: Special Forces Weapon profile, A2 profile with "fat" portion forward of the sight triangle Barrel twist Note: Metric measurements are rounded upwards to the nearest digit. • 1:14: 1 right hand twist every 14 inches (356 mm) .222 Remington or .223 Remington (US M193) • 1:12: 1 right hand twist every 12 inches (305 mm) .223 Remington (US M193) or 7.62×39mm • 1:10: 1 right hand twist every 10 inches (254 mm) 9×19mm NATO • 1:9: 1 right hand twist every 9 inches (229 mm) .223 Remington & 5.56×45mm NATO • 1:7: 1 right hand twist every 7 inches (178 mm) 5.56×45mm NATO (NATO SS109 & US M855) Muzzle device • Type 1 Duckbill: Original three-prong flash hider • Type 2 Duckbill: Also referred to as "three prong." A larger three-prong flash hider • A1 or A1 Birdcage: Also referred to as Birdcage flash hider • A2 or A2 Compensator: Birdcage flash hider with bottom slots closed off to act as muzzle compensator and to prevent dust from being blown into the shooters face while in the prone position • 3.5" Moderator or 4.5" Moderator: Either the 3.5-inch or 4.5-inch baffled moderators • Conical: A conical flash suppressor • ACR Compensator: Special anti-rise muzzle device developed specifically for the Colt ACR • Factory Compensator: Colt Factory muzzle brake compliant with the restrictions of the 1994 Federal Assault Weapons Ban ==References==