300 wsm, The .300 Winchester Magnum—that belted affair based on a shortened Holland and Holland case—was released in 1963 as the last in a quartet of cartridges that redefined magnum performance to the masses. It bettered the velocity of the benchmark .30-06 Springfield by over 200 fps, yet could fit in a standard long action. It drove the .300 Holland & Holland completely out of the lime light, taking the crown as the preeminent .30 caliber magnum.
Fast forward to the beginning of the 21st century, and you’ll see the 2001 release of the .300 Winchester Short Magnum. Loosely based on a shortened .404 Jeffery, this short-action cartridge was designed and hyped to match the ballistics of its older Winchester sibling in a lighter rifle with a more rigid action. It did just that, driving .30 caliber bullets (within reason) at similar velocities to the belted .300 Winchester, but it’s not as simple as that.
Both cartridges come with some points of interest—or gripes, depending on who you ask—that make them unique, and while fans in each camp fervently wave their flags, it may help if we better understood where they’re coming from.
No self-respecting magnum cartridge of the 20th century would have shown its face on the market without the Holland & Holland belt, though very few of them—excepting the straight-walled affairs—needed them at all. That belt was designed for proper headspacing on the sloped-shouldered .375 H&H case (and the .275 H&H Magnum that barely predated it), allowing to feed properly from a box magazine while maintaining the positive headspacing characteristics of the rimmed cases. That belt—often mistaken as making a case stronger—can cause some stretching, and often you’ll see a case separate just north of that belt. The .300 Winchester Magnum was also designed with a very short neck—0.264″ long to be precise—and has been criticized for it. The rule of thumb is that a cartridge should have a neck length of at least one caliber, but I’ve never seen an issue with neck tension in any .300 Winchester, no matter how long or short the bullet. I have seen some issues with the overall length of the case preventing some of the modern bullets—with the really long ogives—being able to function through the magazine in some rifles, but I suppose that comes with the territory.