While the development of the MAS 49 had given France a very utilitarian rifle that could serve as both for both marksmen and grenadiers, it could still be made better. In large part, the change to the 49-56 pattern was motivated by the move to adopt NATO-compatible 22mm rifle grenades. With the new muzzle hardware, several other changes were made. A gas cutoff was added, to prevent wear and tear on the action from grenade use (something that was found to be a real problem on the MAS 49). The gas port was also moved farther down the barrel, and the handguard and barrel were both shortened to make the rifle a bit lighter and handier.

Production began in 1957, and about 175,000 of the rifles were made, seeing as France's standard front-line infantry rifle until the adoption of the FAMAS in 1979.