After Remington released its standard-length, belted 7mm magnum in its new, accurate, budget priced Model 700 rifle in 1962, Winchester was practically on the canvas. It’s competing 264 Win. Mag. was no longer so competitive. The 7mm threw deer and elk-sized bullets just as fast if not faster and went well beyond the 140-grain bullets typically loaded in the 264 magnum. The larger bore didn’t burn out as fast as the throat of the 264, either.
Well, by golly, this was America, land of the 30-30 and 30-06. If Remington could titillate the masses with a silly 7mm cartridge, Winchester could blow their skirts over their ears with an even more powerful 30-caliber magnum. But how to do it?
Weatherby had already maximized the 300 H&H case in full magnum length. Norma had necked down Winchester’s own shorter, standard-length action 338 Win. Mag. case. What was left?
More powder space in a standard length case. Winchester shoved the shoulder forward as far as they dared, leaving just a .264-inch long neck to secure their 150-, 180-, 200-, and 220-grain bullets. That created a reservoir large enough to harbor some 83 grain of water, Dry it out and you had room for more powder than the Norma or H&H could hold. And you had it in a case that would fit common, relatively affordable American rifles like Winchester M70.
300 Winchester Magnum Evolution, History, and Performance — Ron Spomer Outdoors is written by Ron Spomer for www.ronspomeroutdoors.com