The 7mm Mauser, occasionally known as the 275 Rigby, or the 7 x 57mm Mauser is military based cartridge from the famed rifle and ammo designer Paul Mauser. The rifle utilizes a .285 projectile on top of a 2.244 inch case. The round was first adopted by the Kingdom of Spain at the end of the 19th century.
7mm Mauser ammo fired a projectile weighing 173 grains at 2300 feet per second. The 7mm Mauser was, at the time, considered a small bore round, and featured significantly less recoil that previous military rounds of the time.