While full-length handguards are all the rage, Barrett thinks about their firearms a little differently. In the mid-1950s, Eugene Stoner, an often unappreciated genius of American small arms design, crafted the new rifle that became the AR-10 while working for Fairchild-ArmaLite, a California-based aviation tech venture that at the time was exploring the use of lightweight materials used in aircraft fabrication for the production of light, forward-thinking firearms that offered accuracy and mobility in a single package. The Springfield Armory Saint is the gun for everyone, but SIG Sauers M400 Classic nears perfection. We were disappointed in the CMMG Mk4T, which to our eyes looked unfinished. A staff member recently paid $2300 for a complete AR-15 carbine without regret. Most AR15s use a direct impingement gas operating system. On the M400, there is an extension that adds surface area in an L-shape, making it much easier to operate. This does not mean the rifle is full-auto; it only means that the bolt carrier is stronger than a carrier designed for semi-auto making it much tougher and more durable. Depending on your price range, you may or may not find all these features in every AR15. It features M-Lok free-floating handguards and a flat-topped receiver with a rail. Looking past the outdated grip and buttstock, this is a very good rifle that deserved a much better trigger. Well, in the 1990s, after the patents for the original AR-15 and AR-10 that ArmaLite sold to Colt in the 1960s ran out, the inventor was working for Reid Knights Knights Armament Company (KAC) in Florida. Its really a personal preference. But I can say with confidence that these are all good rifles, and I own several of them myself. Since then, the company expanded the line of guns to include a range of variations that fall into three main lines. The PSA 15 is a flat-topped carbine with free-floating M-Lok handguards. According to the National Shooting Sports Foundation, the professional organization of the firearms industry, there are approximately 19.8 million AR15s in circulation in the United States.