The 25 RPM follows the same design philosophy that made the 6.5 and 338 RPM such a standout performer. RPM stands for rebated precision magnum a modern case design built to maximize performance in the lightweight Mark V 6 lug action. The idea is simple create a magnum level cartridge that fits in a lighter more compact rifle without sacrificing velocity or downrange capability. – CARTRIDGE SPECS – Bullet Diameter: .257 (6.35mm) – Common Reference: 25 Caliber – Max Case Length: 3.34 – Bullet: Hammer Custom – Weight 107gr