Nikon’s P-223 scope is factory calibrated for a 55-grain bullet at 3,240 fps. For other weights of bullets, the Nikon “Spot On” tool on the Nikon website can be used to calculate other trajectories. M240B 7.62 and M249 5.56 machine guns roll off the line every day. In fact, Colt’s Mfg. Co. LLC orders its AR-15 sporters from Colt Defense LLC. Both companies are housed in the same plant but are more or less separated by a line on the floor so the same quality that is demanded under mil-spec contracts goes into every AR-15 sporter that leaves the factory. Two qualities at Colt caught my attention immediately: a smart, switched on staff who are enthusiastic about regaining the leadership position the company once had and who are obsessed with listening to their customers about new product development; and a remarkable and overwhelming focus on quality control Colt’s innovative magazine well adapter reduces the .308 lower’s magazine well to 5.56 dimensions. Better yet, the mag well adapter can be used with other .223/5.56 uppers as well. Both the LE901 handguard and Vltor stock accept quick detachable swivels. which includes a complete, in-house, chemical analysis of every batch of steel purchased and, for us AR lovers, a protocol to proof and Magnaflux the bolt and barrel together as a complete assembly that will stay together throughout the manufacturing process. The new Colt 7.62/5.56 modular carbine was a revelation; especially considering it takes only a couple of minutes to make the changeover. The LE901 comes as a .308 Winchester (7.62 NATO) carbine with a 16.1inch, chrome-lined barrel with a 1:12-inch twist and capped off with the highly effective Vortex flash hider. The upper is machined from an aluminum forging to incorporate a monolithic handguard with full length, Picatinny (M1913) top and side rails. This 1-piece design is not only structurally rugged but also facilitates the use of a completely free-floated barrel for optimum accuracy. Attached to the inside of the monolithic handguard is a 180-degree heat shield at the 6 o’clock position underneath the barrel, designed to keep the shooter’s fore-end-grasping hand cool. The separate bottom rail can be removed, but I see no reason to do so. commonality Examining the LE901 upper in more detail reveals the first clue to understanding how Colt designed the switch-caliber carbine. The forward portion of the bolt carrier is massive to enclose the .308-size bolt, which features a spring-loaded firing pin by the way, but the rear of the carrier is the same diameter as that of an AR-15 bolt carrier. Ah-ha, eureka! With its 5.56-dimensioned rear end, the .308 bolt carrier is now compatible with the diameter of the standard AR-15 lower receiver extension tube that houses the buffer and buffer spring, which is clue W W W. G U N S M AG A Z I N E . C O M 41
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