The rifle features Colt’s new monolithic upper receiver. The Colt LE6940 Monolithic Advanced Law Enforcement Carbine, an upgrade of the 6920, have started popping up for sale.The CM901 (Colt Modular) weapons system is based on Colt's existing M16/M4 military designs. Its semi-automatic variant is the LE901-16S. Its caliber and barrel length can be changed without the use of tools. The Colt CM901 is a modular selective-fire rifle.When I purchased it in the March of 2009, the dealer made a big deal that it was from one of the first crates of these guns shipped out of Colt, so I should be very careful to take care of it, and to keep all the boxes, etc. I have a very lightly used Colt M4 Monolithic (LE6940).In addition to an uninterrupted full-length front rail, this upper receiver allows for a free-floated. The Colt LE6943CK Monolithic Upper Assembly feature's Colt's new monolithic upper receiver.
