7x57mm Mauser

From Wikipedia, the free encyclopedia

7x57mm Mauser
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, Boers
Wars	First Rif War, Spanish-American War, Second Boer War
Production history
Designer	Mauser
Designed	1893
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 Mauser cartridge, also known as the 7x57mm, 7 mm Mauser, 7 mm Spanish Mauser and .275 Rigby, was developed by Mauser as a military cartridge in 1893, initially for use by the military forces of Spain. 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's called this chambering the .275 Rigby, after the measurement of a 7 mm rifle's bore across the lands.

1 History
2 Military round
3 Cartridge dimensions
4 Sporting round
5 See also
6 References

[edit] 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 "7x57mm Mauser". It featured an 11 g (175 grain ) bullet with a muzzle velocity of about 700 m/s (2 300+ feet per second ). 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 wind resistance within normal combat ranges.

[edit] Military round

The qualities of the 7x57mm Mauser 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 firing 7x57mm rounds with withering effectiveness, easily outranging the .303 British cartridge as regards accurate long-range fire. The .303 cartridge at that time was still using fine-grain black powder propellant, in contrast to the Mauser's higher-performance smokeless powder. The British kept the .303 cartridge, switched to a smokeless propellant (cordite), and updated their rifle to the Lee Enfield No. 1 Mk III.

[edit] 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.

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.

[edit] Sporting round

7x57mm hunting cartridge

The ballistics of the 7x57mm Mauser quickly became very popular with deer and plains game hunters. The flat trajectory, along with the penetrating effects of the 7 mm bullet's high sectional density, ensured its place as a sportsman's cartridge. It was extremely popular in Africa, where it was used on everything up to and including elephants, for which it was particularly favoured by legendary ivory hunter W. D. M. Bell, who shot 1,011 elephants with the diminutive 7x57mm, when most ivory hunters were using massive large caliber rifles. It was also the favored rifle 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, consistently taking game both large and small with the 7x57mm, a tribute both to the round's dependability and versatility, as well as her outstanding marksmanship. Though not quite so popular today, the 7x57mm is still produced by most major ammunition manufacturers and many modern rifles are available chambered for the cartridge, from custom and mass-market riflemakers in Europe and the USA.

Due to the age and metallurgical characteristics of the rifles for which it was originally designed, many of which are still functioning, most American commercially-manufactured rounds do not exploit the full potential of the cartridge, and opt for lower pressures. Some European-produced rounds are loaded to give higher velocities and pressures, and these can only be safely used in modern rifles chambered for the 7x57mm Mauser cartridge. This is not to say that older rifles, especially the stronger-built military rifles, cannot fire full power loads, but that commercial ammo companies are not willing to take the risk of lawsuits due to catastrophic failures. All firearms should be checked by a competent gunsmith and declared safe before any attempt is made to fire them.

The 7.92x57mm Mauser ("8 mm Mauser") and 7x57mm ("7 mm Mauser") cartridges are by no means the same cartridge, and they cannot be exchanged. Attempts to interchange the two cartridges could (and probably will) result in damage to property, injury and death.