http://www.patreon.com/ForgottenWeapons Cool Forgotten Weapons merch! http://shop.bbtv.com/collections/forgotten-weapons Gas-delayed blowback is a relatively uncommon operating system used in handguns. It is not an efficient mechanism for high-pressure rifle power cartridges, but works well with something like 9mm Parabellum. It tends to provide benefits of light felt recoil and better-than-average accuracy, in exchange for overheating much more quickly than other systems. Contact: Forgotten Weapons PO Box 87647 Tucson, AZ 85754