 The FAL operates by means of a gas-operated action very similar to that of the Russian SVT-40.The gas system is driven by a short-stroke, spring-loaded piston housed above the barrel, and the locking mechanism is what is known as a "tilting breechblock".To lock, it drops down into a solid shoulder of metal in the heavy receiver much like the bolts of the Russian SKS carbine and French MAS-49 series of semi-automatic rifles.