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7x57mm
Ammunition 7x57.jpg
Two 7x57 cartridges next to a 7.5x55 / GP11 (mid), .308 Win and .223 Rem (far right)
Type Rifle
Place of origin  German Empire
Service history
Used by Spain, Mexico, Brazil, Chile, Serbia, Boers
Wars First Rif War, Spanish-American War, Second Boer War
Production history
Designer Mauser
Designed 1893
Variants 7x57mm R (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 gr H2O)
Rifling twist 220 mm (1 in 8.66 in)
Primer type Large rifle
Maximum pressure 390 MPa (57,000 psi)
Ballistic performance
Bullet weight/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)
12.2 g (188 gr) RWS HMK 770 m/s (2,500 ft/s) 3,320 J (2,450 ft·lbf)
Test barrel length: 600 mm (23.62 in)
Source: RWS / RUAG Ammotech[1]

The 7x57mm cartridge, also known as the 7 mm Mauser, 7x57mm Mauser, 7 mm Spanish Mauser in the USA and .275 Rigby in the United Kingdom, was developed by Paul Mauser of the Mauser company in 1892 and adopted as a military cartridge by Spain in 1893.[2] 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 7x57mm has been deservedly 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 Rigby, after the measurement of a 7 mm rifle's bore across the lands.[2]

Contents

History

The Spanish military adopted a new Mauser rifle design in 1893. This took a smokeless powder centerfire cartridge with a bullet with a nominal diameter of 7 mm (0.285 in), and a case length of 57 mm - hence the names "7x57mm Mauser" and "7x57mm Spanish Mauser". It featured an 11 g (175 grain ) bullet with a muzzle velocity of about 700 m/s (2,300+ feet per second ).[2] For the late 19th century, these ballistics were impressive. The change in bullet style, from a rounded tip to a pointed tip, was partially responsible for the cartridge's performance as it significantly reduced air drag within normal combat ranges.

Military round

The qualities of the 7x57mm as a military round were shown in the Spanish-American War and the Second Boer War in South Africa. Teddy Roosevelt and the Rough Riders took very heavy casualties attacking an inferior force armed with 7 mm Model 93 Mauser rifles. Likewise, British soldiers fighting in South Africa were obliged to re-evaluate rifle and ammunition design and tactics after facing Boer sharpshooters and snipers armed with Model 1895 Mauser rifles firing 7x57mm rounds with withering effectiveness, easily outranging the .303 British cartridge as regards accurate long-range fire.[3] The .303 cartridge at that time was still using cordite propellant, in contrast to the Mauser's higher-performance ballistite type smokeless powder.[4] The British modernized the previous .303 British cartridge variants to the Mark 7 variant that like the 7x57mm used smokeless propellant, and updated their rifle to the Lee Enfield No. 1 Mk III.

Cartridge dimensions

The 7x57mm 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.

7 x 57.jpg

7x57mm maximum C.I.P. cartridge dimensions. All sizes in millimeters (mm).

Americans would define the shoulder angle at alpha/2 ≈ 20.55 degrees. The common rifling twist rate for this cartridge is 220 mm (1 in 8.66 in), 4 grooves, diameter of lands = 6.98 mm, diameter of grooves = 7.24 mm, land width = 3.90 mm and the primer type is large rifle.

According to the official C.I.P. guidelines the 7x57mm case can handle up to 390 MPa (56564 psi) piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure to certify for sale to consumers. By contrast, the American industry association SAAMI specifies a maximum pressure of 46,000 CUP.[5] This lower specification is in deference to the weaker actions of the older Mauser 93 and 95 rifles, which are still in circulation.[5]

European 7 mm cartridges all have 7.24 mm (0.285 in) grooves diameter. American 7 mm cartridges have 7.21 mm (0.284 in) grooves diameter.

Sporting round

7x57mm hunting cartridge

The ballistics of the 7x57mm became popular with deer and plains game hunters. The relatively flat trajectory and manageable recoil ensured its place as a sportsman's cartridge. The 7x57mm 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. Bell, who shot 1,011 elephants using a 7x57mm rifle, when most ivory hunters were using larger-caliber rifles. Bell selected the cartridge for moderate recoil, and used 11-gram military full metal jacket bullets for reliable penetration. Bell sectioned an elephant skull to determine the size and location of the brain, and used careful aim to ensure bullet placement in the brain.[2]

The 7x57 was also the favored cartridge of Eleanor O'Connor, wife of famous hunter and author Jack O'Connor. Eleanor accompanied her husband on multiple hunting expeditions all over the world, killing small and large game with the 7x57mm. Though not as popular today, the 7x57mm is still produced by most major ammunition manufacturers and many modern rifles are available chambered for the cartridge.

Due to the age and metallurgical characteristics of the rifles for which it was originally designed, many of which are still functioning, most U.S. commercially manufactured 7x57mm is loaded to lower pressures. European-produced rounds originating from C.I.P. member states are often loaded to give higher velocities and pressures, and these can only be safely used in modern rifles chambered for the 7x57mm cartridge. Older rifles may fire modern loads, but should be checked by a competent gunsmith and declared safe before being fired.

The 7.92x57mm ("8 mm Mauser") and 7x57mm ("7 mm Mauser") cartridges are not interchangeable; attempts to do so may cause damage or potential injury.

See also

References

  1. ^ RWS Ammunition Ballistic Data & Application Consultant
  2. ^ a b c d Jim Wilson "A Perfectly Delightful Cartridge: 7x57 mm Mauser" American Rifleman November 2009 pp.53–55
  3. ^ Mauser Model 95 / Plezier Mauser 7x57mm
  4. ^ David Cushman. "History of the .303 British Calibre Service Ammunition Round". http://www.dave-cushman.net/shot/303hist.html. 
  5. ^ a b Allan Jones, ed. (June 2008), Speer Reloading Manual, #14, pp. 360, ISBN 978-0-9791860-0-4 







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