movie blank cartridges

Years ago, the GUN DIGEST annual had an article on how Hollywood modified firearms to function with blank ammo. Until the Sixties, most movie blanks were loaded with a proprietary (trade secret) powder which included magnesium and a chlorate oxidizer (similar to flashbulb powder) to give an impressive muzzle flash. When fired, the residue contained magnesium oxide-a gritty, sand-like substance. The blanks worked well in the manually-operated revolvers and lever-action rifles (used in Westerns), but QUICKLY fouled the semiautos and machine guns used in WW2 films. By the time of BONNIE & CLYDE and THE WILD BUNCH, many studio armorers were custom loading blanks to optimally function the specific guns used in a film. TRIVIA: the CIVILIAN Colt 1905 .45 pistol will function UNMODIFIED with blanks, but the 1911/1911A1 MILITARY .45 requires a barrel restriction for blanks to generated enough of a recoil impulse to cycle the action. This is because the 1911 pistol has a barrel bushing and a grip safety; both components generate enough friction to require the extra ommph not needed by the 1905 pistol. This is why Bogart used a 1905 pistol in HIGH SIERRA and Gary Cooper's CO used a 1905 pistol in SGT. YORK; apparently Warner Brothers did not have a 1911 pistol suitably tuned to work with blanks. (Coop also fired a captured 9mm Parabellum [Luger] in the latter film-unlike the 1911 .45 used by the REAL Alvin York to drop seven charging Huns with seven shots. Reason: the Luger is another autopistol than will typically work with blanks.)