 The Model 1923 was a heavy submachine gun introduced to potentially expand the Auto-Ordnance product line and was demonstrated for the U.S. Army.It fired the more powerful .45 Remington–Thompson cartridge which fired a heavier bullet at muzzle velocities of about and energy about , with greater range than the .45 ACP.It introduced a horizontal forearm, improved inline stock for accuracy, barrel, bipod, and bayonet lug.