7.65×20mm Longue

The 7.65×20mm Longue (also known as 7.65mm French Longue, 7.65 mm Long, 7.65mm MAS, 7.65×20mm, and 7.65L) was a straight, rimless cartridge used in the French Modèle 1935 pistol, as well as the MAS-38 submachine gun. The cartridge was developed for the United States and secretly produced in quantity too late for its intended use during World War I. The United States scrapped the weapons built for the cartridge between the world wars. France adopted weapons for the cartridge and those weapons saw combat use; so the cartridge is best known by its French name.

The French military were introduced to the cartridge when the US demonstrated the Pedersen device after the end of World War I in Le Mans and again when John Browning exhibited a carbine in the same caliber in 1920. The US .30 Pedersen cartridge (Auto Pistol Ball Cartridge caliber .30 Model of 1918 or .30-18 Automatic) used in the Pedersen device was the basis for the 7.65×20mm Longue. The cartridge dimensions were identical, although Pedersen device cartridges were loaded with a slightly heavier 80 gr bullet which achieved a velocity of 1300 ft per second in the longer barrel of M1903 Springfield rifles.

Remington Arms produced 65 million cartridges for the Pedersen device between 1918 and 1920. French 7.65×20mm Longue ammunition was manufactured in quantity from approximately 1935 to 1960.