Colt Automatic Rifle Colt Automatic Rifle or Colt Light Machine Gun is a 5 . 56 mm NATO , open - bolt , full - automatic - only firearm developed by Colt Defense . It is based on the M16A2 / A4 , and its forward hand - grip has a distinctive squared - off shape , pistol grip , carrying handle and integrated bipod . It is one of many SAW - type firearms that have been developed from the AR - 15 . Others include the Colt CMG - 1 machine gun and CAR - 15 Heavy Assault Rifle . Overview . The Colt Automatic Rifle is the name of a current product , but Colt has developed a number of similar weapons since the company obtained the rights to produce the Armalite AR - 15 family at the end of the 1950s . The name " Colt Automatic Rifle " should not be confused with Colt ' s original CAR - 15 weapon family . Originally known as the Colt M16 LMG or simply as the Colt LMG ( LMG standing for Light Machine Gun in this context ) , this weapon was developed as a join venture by Colt and Diemaco , a Canadian firm licensed by Colt to produce variants of the M16 family . Diemaco was recently purchased by Colt bringing that story full circle . The Colt / Diemaco weapon can trace its lineage back to a number of weapons developed both at Colt and by the US military . These weapons were all designed to fill the role of the Browning Automatic Rifle . The BAR was originally planned to have been replaced by the M15 , a variant of the M14 designed to fill a similar role . With the cancellation of that weapon , the BAR was initially replaced by the M14 itself , and then by a variant of that weapon , the M14A1 . When the M14 was removed from frontline service the US automatic rifleman was given an M16A1 and was supposed to use this weapon set to the fully automatic setting while the rest of the squad used the rifle in the semi - automatic setting . Throughout the period between the introduction of the M16 and the introduction of the M249 as a purpose - built squad automatic weapon at the end of the SAW trials , interim weapons were developed and tested in order to fill the gap . Colt Model 606 CAR - 15 Heavy Assault Rifle M1 and Heavy Assault Rifle M2 . Colt made a version of the M16 with a heavier barrel for sustained automatic fire . Along with a bipod , it weighed a pound more than a normal M16 . The Army purchased less than 200 for use in the Small Arms Weapons System ( SAWS ) program , not to be confused with the Squad Automatic Weapon ( SAW ) program . Colt engineer Rob Roy also created a belt fed version of the 606 , named the " Heavy Assault Rifle M2 , " based on a feed system developed for the AR - 10 by Eugene Stoner and John Peck back at Armalite . This weapon was also sent to the US Army for testing , in a variety of capacities ( even as a possible helicopter door gun ) , but was rejected . WAK " Interim SAW " and the BRL XM106 . At the behest of the USMC , WAK Inc . started work on an " Interim SAW " in 1977 . This was to provide a more solid automatic rifle to replace the practice of the automatic rifleman switching his weapon to full - auto , and to provide this capability until the US Army ' s SAW trials had been completed . The WAK SAW was essentially an M16A1 converted to fire from an open bolt , accompanied by a special buffer , and featuring a specially made compensator . In 1978 the US Army ' s Ballistic Research Laboratory decided to build upon the WAK idea to create a contender for the SAW trials , given the designation XM106 . The BRL gun differed primarily in having permanently fixed handguards and a special quick - change barrel system . The handguards also had an M2 bipod originally for the M14 rifle and a vertical foregrip fashioned from spare A1 pistol grips fitted . Early XM106s also had the front sight moved forward along the barrel to create a longer sight radius for more accurate long range fire , but this was dropped from later versions . In the end the Army used the XM106 as more of a control variable during the competition and selected the XM249 , better known as the M249 Squad Automatic Weapon . The Colt / Diemaco LMG . During the 1980s Colt decided to expand on the basic ideas that had been exposed in the WAK and BRL guns . The weapon was essentially a modified M16A1 with a new square handguard to cover the enlarged gas tube , a carry handle on top of this handguard , with a hydraulic buffer and the ability to fire from an open bolt . An angled foregrip was added to the handguard to improve handling as an automatic rifle . Rear sights later featured on the M16A2 were also introduced , and the weapon could only fire on the fully automatic setting . Colt initially packaged these weapons with the MWG 90 - round " snail drum " ( This was before the introduction of the Beta Systems C - Mag ) . Colt had also originally used the M60 bipod , but switched this to a proprietary design that was lighter for the subsequent Model 750 The Colt Model 750 was an improvement of the basic principle of the Colt LMG , developed jointly by Colt and Diemaco with an eye toward the Canadian Army ( though they would eventually select the FN MINIMI ) . The improved version featured all A2 parts and is essentially the same as original variant externally except for the redesigned vertical foregrip , now of a straight cylindrical style that is ribbed . This weapon was marketed by Diemaco as the Diemaco C7 Light Support Weapon ( LSW ) or simply as the LSW . Colt and Diemaco further improved on the design , adding a flat top carry handle and a further improved bipod to the weapon in the ' 90s . Colt refers to it as the Model 950 , but markets it as the Colt Automatic Rifle , and until their purchase by Colt , as the Diemaco LSW . Because of the Colt - Diemaco partnership on this system , it was the only weapon in their product line to feature A2 rear sights , and when modified a detachable carry handle with A2 rear sights ( the majority of Diemaco ' s product line had A1 rear sights , and they actually developed a detachable carry handle with A1 rear sights ) . A maple leaf is stamped on the lower receiver of current Colt Automatic Rifles .