AA-52 machine gun

The AA-52 (Arme Automatique Transformable Modèle 1952, "Transformable automatic weapon model 1952") is one of the first French-produced guns of the post World War II era. It was manufactured by MAS (an abbreviation of Manufacture d'Armes St. Etienne - one of several government-owned arms factories in France) The AA-52 is still used today as a vehicle-mounted weapon due to large quantities in service, but has been replaced by the Belgian FN MAG for helicopter use, starting with the EC 725 Caracal of the Special Operations units and the Air Force Search and Rescue teams. The AA-52 had been phased out for infantry use in favour of the lighter FN MINIMI for a few years; the replacement of the AA-52 by the FN MAG as the standard infantry GPMG is now taking place (in 2008).

The AA-52 machine gun was conceived and developed following the French military's experiences in Indochina during the early 1950s. At that time, the French army was equipped with an assortment of weapons from British and American sources, as well as some German weapons from the Second World War.
Effective supply of ammunition and replacement parts was an almost insoluble task and the army decided to adopt a standard machine gun. The result was the AA-52, conceived for easy production. The construction was of simple welded stamped sheet steel.

The AA-52 is a peculiar weapon among modern machine guns by its blowback system of operation. The AA-52 uses Lever-delayed blowback. When firing, the pressure pushing the case head rearward initiates an impulse on a cam that sends the bolt carrier rearward. After a certain distance, a link (in this case the firing pin) pulls the bolt head, hence extracting the spent case. Since there is no primary extraction, the chamber is fluted to allow powder gases to flow back, unsticking the case from the wall chamber like on H&K type Roller-delayed blowback weapons.
The AA-52 can be used as a LMG with a bipod or HMG with a tripod. When used with a tripod for continuous fire, the gun is fitted with a heavier barrel. In the LMG configuration, the AA-52 is a relatively light weapon to carry. To change the barrel, it is simply necessary to press a latch and rotate 1/4 turn.