The .338 Weatherby RPM (Rebated Precision Magnum) is a modern .338-caliber cartridge designed to deliver heavy-bullet magnum performance from standard-size, lightweight rifle actions. It targets larger big game and longer-range hunting with substantial energy.

The .338 Weatherby RPM is the large-bore member of Weatherby's Rebated Precision Magnum family, applying the same concept as its siblings — magnum performance from a rebated-rim case that fits standard six-lug actions — to the heavy-hitting .338 caliber. The aim was to deliver serious .338-caliber energy in a lighter, more standard, carry-friendly rifle than traditional large magnums require. Ballistically the .338 Weatherby RPM drives heavy .338-caliber bullets at high velocity, producing strong retained energy well suited to larger big game and longer-range hunting where bullet weight and energy matter. As with all heavy-bore magnums, that performance comes with significant recoil, a tradeoff hunters accept in exchange for the energy the large bullet delivers on big animals. As a newer cartridge in a proprietary family, its rifle and ammunition availability is narrower and centered on Weatherby. It offers hunters a .338-class option in the modern lightweight-rifle format that the RPM line was built around, distinct from established large magnums like the .338 Win Mag and the longer-range .338 Lapua. Today the .338 Weatherby RPM is used for big-game hunting and long-range target shooting, with availability centered in Weatherby rifles and ammunition. Its pairing of heavy .338-caliber performance with a standard-action, lightweight-rifle format is what defines its place in the lineup.

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