Weatherby Select Plus Barnes TTSX .338 WBY RPM 225 Grain PT Brass Cased Rifle Ammo 20 Rounds. The goal was to fit a large caliber bullet into a lightweight backcountry rifle that could take down all of North America's big game. The 338 RPM is based off of the 6.5 RPM necked up to accept a .338 caliber bullet. The case features a large body diameter low body taper and 35-degree shoulder creating a larger powder capacity leading to higher velocities. Specifications for Weatherby Select Plus Barnes TTSX .338 WBY RPM 225 Grain PT Brass Cased Rifle Ammunition: Manufacturer: Weatherby Caliber: .338 Weatherby Rebated Precision Magnum Number of Rounds: 20 Bullet Type: Jacketed Soft Point Boat Tail (JSPBT) Bullet Weight: 225 grain Cartridge Case Material: Brass Muzzle Velocity: 2800 ft/s Muzzle Energy: 3917 ft-lbs Application: Big Game Hunting Primer Style: Centerfire Package Contents: Weatherby Select Plus Barnes TTSX .338 WBY RPM 225 Grain PT Brass Cased Rifle Ammunition What is Weatherby Select Plus Barnes TTSX .338 WBY RPM 225 Grain PT Brass Cased Rifle Ammunition good for? The manufacturer thinks that it is best for hunting big game.Weatherby B338225TTSX: Select Plus Barnes TTSX .338 WBY RPM 225 Grain PT Brass Cased Rifle Ammo 20 Rounds