Introduced in 1963, the 300 Win Mag came out just before the catastrophic takeover of Winchester by Olin Industries, which resulted in the well-documented gutting of Winchester gun quality and the near destruction of that Company — it never has and never will fully recover. Winchester’s goal with the 300 Win Mag was to allow it to offer a standard-length 30-caliber magnum that came close to duplicating performance of the 300 Weatherby Magnum. It was worth a try. While it fell short of that lofty goal, partly because the 300 Win Mag necessarily worked at significantly lower pressure than the Weatherby loads of that era and partly because it had significantly less case capacity, it still offered a worthwhile improvement over any existing 30-caliber chambering available in the U. S. that would work in a standard-length action. Worldwide, the 300 Win Mag has become one of the most recognized and used hunting rounds for all big-game applications. In Scandinavia, perhaps surprisingly, it is the single most-used hunting round. With the best modern propellants and bullets, performance of the 300 Win Mag is impressive. Not too long ago, loading manuals often listed the 300 Weatherby and 300 Win Mag one after the other in alphabetical order or in order of power. In either case, for decades the two were presented one after the other. Partly because of this, a surprising number of 300 Win Mag chambered guns were destroyed when the inattentive handloader inadvertently used 300 Weatherby Magnum data for his 300 Winchester Magnum loads. As was a host of standard belted–magnum cartridges, this case was derived from the circa 1912, 375 H&H.