After World War II, the French Army commissioned the three major state-owned small arms factories (Tulle, St. Étienne, and Châtellerault) to design a new 9×19mm submachine gun to replace the low-powered MAS 38. The Army expressed a desire that entrant designs should feature both a folding stock and rotating magazine housing.
The MAC 47 was one of two designs from Châtellerault that were submitted to French trials. It was tested against rival designs, including Tulle's MAT-49, St. Étienne's MAS 48, Châtellerault's own MAC 48, and a third-party entry from FN Herstal. The MAC 47 was unsuccessful on account of reliability issues, ergonomic concerns, and a user-unfriendly internal mechanism. The MAT-49 was accepted as the French Army's new submachine gun and thus all development of the MAC 47 came to an end.
The MAC 47 was a blowback-operated submachine gun of an unconventional design. The return spring was located near the trigger mechanism rather than in the upper part of the body and ran across the width of the gun. The bolt was operated by a swinging lever which was attached to the spring. When the bolt retracted, the spring would tighten in a torsion motion and bolt lever would swing forward, pushing the bolt back. Cocking was achieved by flicking a hinged lever that folded underneath the trigger guard.
The unorthodox internal operation of the MAC 47 was a sound concept but flawed in practice. The return spring wore out very quickly and thus the fire rate became increasingly protracted the more the gun was used. Given enough time, the spring would lose the tension required to push the bolt forward at all.
The first prototypes of the MAC 47 featured a single-strut underfolding stock made from sheet metal, which was criticized for being uncomfortable to hold. Subsequent prototypes replaced this stock with a wireframe side-folding stock, within which there was a metal brace that would slot into the ejection port when the stock was folded, both protecting it from dirt fouling and also preventing it from being discharged accidentally. Perforated barrel housing was also added to later prototypes. It fed from MP40 magazines.