Remington High Performance Rifle 375 Remington Ultra Magnum 270gr SP Rifle Ammo - 20 Rounds - Proof of Remington's dedication to providing you with the widest selection of centerfire ammunition in the industry, their High Performance Rifle series consists of a multitude of calibers and popular bullet styles to match your specialized hunting and shooting pursuits. All assembled with premium components and the ultra-tight tolerances that put more home reloading presses on the back shelf than any other brand. Remington High Performance Rifle. Premium Components Ultra-Tight Tolerances Specialized Hunting and Shooting Round Browse all 375 Remington Ultra Magnum Ammo.