The MAS-49 is a French semi-automatic rifle that replaced various bolt action rifles as the French service rifle. The MAS-49 and MAS 49/56 use a direct gas impingement system with no gas piston. In this system gas is vented from a port on top of the barrel and piped directly into an open cylindrical hollow located in front and on top of the bolt carrier. The system has the advantage of not depositing gas fouling on the bolt itself, a separate part located underneath the bolt carrier. Many MAS-49/56 rifles were imported as surplus in the USA and had been rechambered to fire the 7.62x51mm NATO round.
