33mm A.P.X.

The 33mm APX (French: Ateliers des Puteaux—"Puteaux workshops") was a series of 33 mm caliber autocannon manufactured in France during the early 1930s for use in aircraft.

The weapon was originally designed to be fitted to the Farman F.1010, a low-wing monoplane test-bed aircraft built to trial the cannon.

[1][2] Constructed by Ateliers des Puteaux, the cannon were tested by the French Government in the 1930s and intended to be shot through the propeller hub of an inverted V8 aircraft engine - but were not put into large scale production.

[3] A number of variants were produced in the early 1930s, with differing muzzle velocity, fire rates and ammunition capacities - some designed specifically for the moteur canon (motor cannon) role.

[4] From the mid-1930s onwards, further development was conducted into following-on from the Oerlikon license produced cannons, including a new operating system to increase rate of fire, which eventually resulted in the famed H.S.404 auto cannon.