From the Sisk rifle, and several other .300 Win. Mag. rifles with 24" barrels, propellants such as IMR 4350 and Reloder 17 produced the highest velocities with 150-gr. bullets.

Winchester brought its .300 Win. Mag. to market in 1963, but it didn't take the shape of a standardized version of the .30-.338. Instead Winchester pushed the shoulder forward about 1/8 inch, thus ...