Muzzle velocity
The ARL V 39 mounted the 75mm high-velocity APX gun. It was a modification of the 75mm 1929 casemate fortress gun. Muzzle velocity reached 400 m/s for high explosive rounds and 570 m/s for armor-piercing rounds. Penetration tests found that the armor-piercing shell had 50 mm of penetration at . Instrumentation included two sight and stereoscopic rangefinders, allowing for shots at up to distance. Traverse angles were 7° left and right and -10° to 30° vertically. When transporting the gun barrel could be drawn into the body to reduce the total length. The gun had a semi-automatic breech mechanism, automatic charging, and a data recorder.