The 50 Alaskan was created by Harold Johnson, Alaska, in the 1950s. It�s based on a straighten 348 WCF to accept the .512 inch bullet. Since the rifle was designed for use on Alaska�s great bears, Johnhnson cut 720-grain boat-tail .50 BMG bullets in half, seating the 450-grain rear half upside down in the fireformed .50-caliber case. It didn�t take Johnson long to find out that the 450-grain truncated shaped �solid� would shoot through a big brown bear from any direction, claiming in 1988, �I never recovered a slug from a bear or moose, no matter what angle the animal was shot at.� Harold�s favorite load in the .450 Alaskan was 51.5 grains of IMR-4198 with a Barnes 400-grain flatnose ,jacketed bullet for about 2,100 fps and just under 4,000 foot-pounds (ft-lbsj of muzzle energy, so it�s logical to assume he knew the .50 would surpass the .450 Alaskan owing its slightly larger powder capacity and increased expansion ratio. 

This text is based on information from “Cartridges of the World”, Hodgdon reloading manual, the cartridge designer and/or own resources.