The FBP m/976 submachine gun was developed in Portugal by arms-making factory Fabrica de Braco de Prata, and adopted by Portuguese military in 1976. This weapon can be considered as an evolution of the earlier FBP m/948 submachine gun, which it replaced in service.
FBP m/976 submachine gun is a simple blowback weapon that fires from open bolt, in single shots of full automatic mode, thanks to the combined safety / fire mode selector lever, located on the left side of the trigger unit, above the trigger. The bolt is of simple design, with large diameter return spring that requires no additional guides. Gun is equipped with grip safety which locks bolt in forward or rearward position. Barrel can be fitted with optional screw-on barrel jacket. L-shaped flip-up back sight has settings for 50 or 100 meters. Gun is equipped with sliding, telescoping buttstock made of steel wire, which is patterned after US M3 submachine gun.