7x57mm Mauser

7×57mm
Two 7×57mm cartridges next to a 7.5×55mm/GP11 (mid), .308 Win and .223 Rem (far right)
Type	Rifle
Place of origin	German Empire
Service history
Used by	Spain Dominican Republic Colombia Mexico Brazil Chile Kingdom of Serbia Venezuela Boers
Wars	First Rif War Spanish–American War Second Boer War Macedonian Struggle Balkan Wars First World War Spanish Civil War other conflicts
Production history
Designer	Paul Mauser
Designed	1892
Variants	7×57mmR (rimmed)
Specifications
Parent case	none
Case type	Rimless, bottleneck
Bullet diameter	7.24 mm (0.285 in)
Neck diameter	8.25 mm (0.325 in)
Shoulder diameter	10.92 mm (0.430 in)
Base diameter	12.01 mm (0.473 in)
Rim diameter	12.10 mm (0.476 in)
Rim thickness	1.15 mm (0.045 in)
Case length	57.00 mm (2.244 in)
Overall length	78.00 mm (3.071 in)
Case capacity	3.90 cm3 (60.2 gr H2O)
Rifling twist	220 mm (1 in 8.66 in)
Primer type	Large rifle
Maximum pressure (C.I.P.)	390.00 MPa (56,565 psi)
Maximum pressure (SAAMI)	351.63 MPa (51,000 psi)
Ballistic performance
Bullet mass/type Velocity Energy 9.0 g (139 gr) RWS KS 900 m/s (3,000 ft/s) 3,240 J (2,390 ft·lbf) 10.5 g (162 gr) RWS ID Classic 800 m/s (2,600 ft/s) 3,360 J (2,480 ft·lbf) 11.2 g (173 gr) RWS HMK 770 m/s (2,500 ft/s) 3,320 J (2,450 ft·lbf) 11.2 g (173 gr) Factory Military 700 m/s (2,300 ft/s) 2,746 J (2,025 ft·lbf)
Source(s): RWS / RUAG Ammotech

The 7×57mm cartridge, also known as the 7mm Mauser, 7×57mm Mauser, 7mm Spanish Mauser in the USA and .275 Rigby in the United Kingdom 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. It is recognised as a milestone in modern cartridge design, and although now obsolete as a military cartridge, it remains in widespread international use as a sporting round. The 7×57mm has been described as "a ballistician's delight". Many sporting rifles in this calibre were made by British riflemakers, among whom John Rigby was prominent; and, catering for the British preference for calibres to be designated in inches, Rigby called this chambering the .275 bore after the measurement of a 7 mm rifle's bore across the lands.

Paul Mauser visited the Kingdom of Spain in 1892 after delivery of trial rifles in 1891 and brought with him a new rifle designed to use a new cartridge of 7 mm caliber which he had developed for use with the than new smokeless propellant introduced as Poudre B in the 1886 pattern 8mm Lebel that started a military rifle ammunition revolution. This new rifle featured a new internal box magazine where the cartridges were stored in a staggered column. The Spaniards were so impressed with this new arm and its new 7×57mm Mauser cartridge that they not only placed an order with Mauser but also awarded him the Grand Cross of the Spanish Military Order of Merit, the highest decoration Mauser ever received.

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.