The .300 WSM (Winchester Short Magnum) is a centerfire rifle cartridge introduced in 2001, designed to deliver .300-magnum-class performance from a shorter, fatter case that fits compact short-action rifles. It is a popular big-game and long-range hunting cartridge.

The .300 WSM was introduced by Winchester in 2001 as the flagship of the "short magnum" concept — a design movement aimed at delivering magnum performance from a shorter, wider case that fits in compact short-action rifles rather than the longer actions traditional magnums require. The goal was magnum power in a lighter, handier rifle. Ballistically the .300 WSM fires .30-caliber bullets — commonly 150 to 200 grains — at high velocity comparable to the longer .300 Winchester Magnum, producing a flat trajectory and strong retained energy for big game at extended range. The short, efficient case is its defining feature, allowing that performance in a more compact package. Its recoil is significant, in the magnum class, consistent with the energy it delivers. The short-magnum family generated considerable interest in the 2000s, and while the broader category's popularity has varied over time, the .300 WSM established itself as the most enduring and well-supported of the group, retaining solid rifle and ammunition availability. Today the .300 WSM is used for big-game hunting and long-range target shooting, with steady ammunition availability. Its combination of magnum-class .30-caliber performance in a compact short-action package is why it became the most successful of the short-magnum cartridges.

General information about this caliber — not a recommendation for this specific firearm.