The 7×57mm Mauser (designated as the 7 mm Mauser or 7×57mm by the SAAMI and 7 × 57 by the C.I.P.) is a first-generation smokeless powder rimless bottlenecked rifle cartridge. It was developed by Paul Mauser of the Mauser company in 1892 and adopted as a military cartridge by Spain in 1893. It was subsequently adopted by several other countries as the standard military cartridge, and although now obsolete as a military cartridge, it remains in widespread international use as a sporting round. The 7×57 Mauser (originally known in Britain as the .275) was a popular stalking cartridge and sporting rifles in this chambering were made by the famous British riflemakers, such as John Rigby Holland and Holland, Westley Richards and others. British cartridge nomenclature designated caliber in inches, and the cartridge was known as the .275 bore after the measurement of a 7 mm rifle's bore across the lands.
The 7×57mm cartridge has 3.90 ml (60 grains H2O) cartridge case capacity. The exterior shape of the case was designed to promote reliable case feeding and extraction in bolt-action rifles and machine guns alike, under extreme conditions.
The ballistics of the 7×57mm became popular with deer and plains game hunters. The relatively flat trajectory and manageable recoil ensured its place as a sportsman's cartridge. The 7×57mm can offer very good penetrating ability due to a fast twist rate that enables it to fire long, heavy bullets with a high sectional density. This made it popular in Africa, where it was used on animals up to and including elephants, for which it was particularly favoured by noted ivory hunter W.D.M. "Karamojo" Bell, who shot about 800 African elephants with 1893 pattern 7×57mm military ball ammunition using Rigby Mauser 98 rifles, when most ivory hunters were using larger-caliber rifles. Bell selected the cartridge for moderate recoil, and relied on the 11.2-gram (172.8 gr) long round-nosed military full metal jacket bullets for penetration.
