Despite the name this cartridge was invented by P.O. Ackley a prolific American wildcatter. Wildcat cartridges are ones that are not made to a standard adopted by any major manufacturer.
This particular cartridge could send a .22 caliber round 5,000 fps (1,524 m/s). The case it uses in this picture is that of a .378 Weatherby Magnum necked down to hold a .223 caliber bullet, but another design of the same name used .50 BMG cases.
Good eye. Just fixed it.
For anyone curious the title had “it’s” instead of the correct “its”.