Although marketed as a .44 caliber, the .44 Magnum and its parent .44 Special are actually .429-.430 caliber. The .44 designation is a carryover from the early measurements of heeled bullets, used in the later 19th century. In those times, bullets were measured on the outside of the cartridge, not the inside of the cartridge. After the .44 Russian was developed, the forefather of the .44 Special and thus the .44 Magnum, the measurement of bullet caliber was taken from inside of the cartridge, resulting in .429 caliber. Instead of confusing buyers who were used to .44 caliber revolvers, the original .44 designation was kept for market recognition.