7x57mm Mauser

Infobox Firearm Cartridge
name=7x57mm


caption=Two 7x57 cartridges next to a 7.5x55 / GP11 (mid), .308 Win and .223 Rem (far right)
origin=flagcountry|German Empire
type=Rifle
service=
used_by=Spain, Boers
wars=First Rif War, Spanish-American War, Second Boer War
designer=Mauser
design_date=1893
manufacturer=
production_date=
number=
variants=7x57mm R (rimmed)
is_SI_specs=yes
parent=none
case_type=Rimless, bottleneck
bullet=7.24
neck=8.25
shoulder=10.92
base=12.01
rim_dia=12.10
rim_thick=1.15
case_length=57.00
length=78.00
case_capacity=3.90
rifling= 220 mm (1 in 8.66 in)
primer=Large rifle
max_pressure=390
is_SI_ballistics=yes
bwunit=gram
bw1=9.0
btype1=RWS KS
vel1=900
en1=3240
bw2=10.5
btype2=RWS ID Classic
vel2=800
en2=3360
bw3=12.2
btype3=RWS HMK
vel3=770
en3=3320
bw4=
btype4=
vel4=
en4=
bw5=
btype5=
vel5=
en5=
test_barrel_length=600 mm (23.62 in)
balsrc= RWS / RUAG Ammotech [ [http://www.rws-munition.de/en/rifle_cartridges/ballistic_data.htm?navid=10 RWS Ammunition Ballistic Data & Application Consultant] ] 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 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.

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 ). 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.

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 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.

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.

porting round

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. It 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."

ee also

*List of rifle cartridges
*7 mm caliber

References

* [http://www.rifleshootermag.com/featured_rifles/plezier_071907/ Mauser Model 95 / Plezier Mauser 7x57mm]
* C.I.P. decisions, texts and tables ( [http://www.cip-bp.org/index.php?id=tdcc-telechargement free current C.I.P. CD-ROM version download (ZIP and RAR format)] )