According to my friend David Faubion, editor of the Book of the AR-15 and other KSE-OSG special publications, Bravo Co.’s BCM4 is “the gun to have if I were only going to have one gun to guard all that’s dear to me.” That’s an awfully strong endorsement, and it carries a lot of weight because David is thick into AR-type guns—rifles, carbines, and pistols. I’ve lost track of the number of special ARs David has built himself, not to mention the myriad factory-made ARs that he’s owned. He hunts with ARs, he trains with ARs, he shoots them for fun, and he’s won more than a few informal industry competition matches with them. His word is...