This is a NIB Colt model MT6400C. It has the 16" M4 barrel with the factory-installed LEO-type compensator and side sling adaptor. Not sure if chrome lined. A3 upper with M4 mark and feed ramp cuts, with carry handle. Not sure why, but this model came with the standard A2 stock. If you like, I can substitute an M-4 stock (non-Colt), in one of the six positions you desire. New in the box with all Colt accessories. Please add $20 for shipping to your FFL.