AR - 15 variants This article is a review of many variations of the AR - 15 family of weapons . Weapons patterned on the original ArmaLite AR - 15 have been produced by numerous manufacturers and have been used by nations around the world , some of which created their own variations . The tables here are split in a variety of categories , and provide an overview of different subtypes of the platform . For purposes of these tables , bold model numbers are weapons used ( or previously used ) by the U . S . Military while " italic " model numbers are weapons for commercial or export sale . See " Glossary of terms " for an explanation of each column . Numbered Colt military models . Colt has been the most visible producer of weapons of the AR - 15 pattern , and the military designation M16 is 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 “ RO . ” For the purposes of this table , the RO 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 . Numbered Colt civilian models . Colt ’ s civilian line 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 . 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 . Colt Canada model changes and comments . When Diemaco became Colt Canada the marketing names for a number of products were changed , though some remained the same . Those that changed are listed below , with comments on what major changes Colt Canada made the models . Glossary of terms . Stock . " Fixed Stocks " " Retractable Stocks " Barrel twist . Note : Metric measurements are rounded upwards to the nearest digit .