The 13.2 mm Breda Model 31 was a widely used Italian heavy machine gun produced by Società Italiana Ernesto Breda and used by the Italian Navy and Italian Army during World War II. At sea it was employed as a light anti-aircraft gun, while on land it was mounted on armored command vehicles where it was used as a heavy machine gun. After World War II it remained in use aboard the patrol boats of the Guardia di Finanza.

The Breda Model 31 was a license built copy of the French Hotchkiss M1929^[3] machine gun. Breda acquired a production license in 1929, but it did not enter production until 1931. The Model 31 was often mounted on single and twin mounts aboard surface ships and on a disappearing twin mount aboard submarines.^[4] The Model 31 was intended to provide close-range air defense, but like its counterparts in other nations, these small-caliber guns were found incapable of defending against low-level torpedo-bombers or high altitude level-bomber attacks because their bullets were too light and short ranged.^[5] Although a reliable gun with good performance, it was later replaced by the Breda 20/65 Mod. 1935.

The Model 31 was a gas-operated, air-cooled machine gun with a tilting bolt action. It was fed by top mounted, semi-circular, thirty round magazines, with cooling air drawn through the sleeve to fins along the barrel.^[6]

Ship classes that carried the Breda Model 1931 include:

• Italian Navy
• Swedish navy – designated 13,2 mm kulspruta M/It (13,2 mm ksp M/It)^[7]