Weatherby Select Plus .338 RPM 225 Grain Hornady Interlock Brass Cased Centerfire Rifle Ammo 20 Rounds. 5 RPM necked up to accept a 338 caliber bullet. The 338 RPM was designed to take advantage of Weatherby 6-Lug action to get magnum performance in a 5lb rifle. The large body diameter low body taper and 35-degree shoulder mean that case capacity is greatly increased leading to higher velocities. Specifications for Weatherby Select Plus .338 RPM 225 Grain Hornady Interlock Brass Cased Centerfire 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 Package Type: Box Included Accessories: None Primer Style: Centerfire G1 Ballistic Coefficient: 0.397 .397 Color: Brass Package Contents: Weatherby Select Plus .338 RPM 225 Grain Hornady Interlock Brass Cased Centerfire Rifle Ammunition What is Weatherby Select Plus .338 RPM 225 Grain Hornady Interlock Brass Cased Centerfire Rifle Ammunition good for? The manufacturer says that it is best for hunting big game.Weatherby H338225IL: Select Plus .338 RPM 225 Grain Hornady Interlock Brass Cased Centerfire Rifle Ammo 20 Rounds