"In general, I prefer to give weapons functional names and avoid getting wrapped up in specific designations used by manufacturers or the military. Because our weapons must, for technical reasons, occasionally differ functionally from the weapons upon which they are based (different caliber, charging handle placement, receiver height, stock shape/length, etc.) giving them a more utilitarian name helps negate some of the potential pedantry over those deviations.There are no AR-15s, Colt Commandos, Browning Hi-Powers, BFRs, M1 Garands, Winchester 1886s, 1887s, or 1892s in Fallout: New Vegas — just Service Rifles, Assault Carbines, 9mm Pistols, Hunting Revolvers, This Machine, Brush Guns, Lever-Action Shotguns, and Cowboy Repeaters.That's also why there are no M1911s or Thompsons in Honest Hearts, but you'll find plenty of .45 Auto Pistols and .45 Auto Submachine Guns."
— Joshua Sawyer, explaining on Bethesda forums why New Vegas plays the trope straight, as archived by the Independent Fallout Wiki
