I was in Dick's and looked at a bushmaster carbine w/MOE fore-end. The lower and upper receivers were carbon (the whole thing weighed no more than a .44mag). The sales clerk said that the carbon receivers had been tortured tested and "they couldn't make 'em fail". I 'sure' there's no conflict of interest, since he just works there for retail wages but 2nd, 3rd, & 4th, opinions would be appreciated.