The 400 Cor-Bon was designed by Cor Bon's Peter Pi and introduced in 1995. Using a slightly bottle-necked case with a base diameter ofr .471-inch, the .900-inch case is necked down to take a .401-inch bullet, essentially a .45 ACP case necked down. With bullets from 115 to 165 grains velocity gains over the 45 ACP are significant, but the cartridge can be housed in a standard 1911 frame, the conversion requiring only a barrel and recoil spring. Velocities approach the 10mm, but with ligher bullets...which produce less recoil. the 400 Cor-Bon is an excellent personal defense cartridge, but no major manufacturer has adopted it, and Cor-Bon is the primary supplier of ammunition. Barrels and appropriate springs for conversion are readily available. —
Craig Boddington