7×57mm Mauser

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 cartridge is today often erroneously referred to as the ".275 Rigby": Rigby the maker contributed to this by selling barrels on their rifles marked “.275 Rigby” and ammunition boxed as “.275 Bore Rigby Special” and Kynoch (the major UK ammunition manufacturer of the period) sold the cartridge in boxes labeled .275 (Rigby) but it is doubtful the cartridge was ever referred to as the ".275 Rigby" during its golden period, although as early as 1941 Kynoch sales literature described the cartridge as .275 Rigby. Also referred to in the 1912 BSA firearms catalog as .276 caliber and 7mm interchangeably, and offered as a caliber option in the sporting model Lee Enfield rifles.