British
The .303 British (7.7 x 56 mm R) is a rifle and machine gun cartridge first developed in Britain in the 1880s as a blackpowder round, later adapted to use cordite and then smokeless powder propellant. It was the standard British and Commonwealth cartridge from 1889 until the 1950s, when it was replaced by the 7.62 x 51 mm NATO round, and in the 1980s by the .223 NATO in most roles. It is a rimmed cartridge and is therefore not entirely suitable for use in modern automatic weapons, but remains popular due to the large number of surplus military rifles chambered for the round which have been released to the civilian market, some of which have subsequently been modified for sport.
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History
The Cartridge, S.A., Ball, Magazine Rifle, Mark I Solid Case, .303inch was first introduced with the Lee-Metford rifle in 1889. In its original form, the round was a 215 grain round-nosed cupro-nickel jacketed bullet propelled by 71.5 grains of RFG2 Blackpowder, giving it a muzzle velocity of 1830 feet per second and a chamber pressure of about 19 tons per square inch. Blackpowder is not very dense, and the charge had to be pressed into a solid pellet in order to fit inside the round. The rimmed cartridge made it easy to extract spent rounds from the receiver, although it did make them somewhat harder to stack in a magazine.
Cordite was used as a propellant from 1891 and the first adopted cordite cartridge, the Cartridge S.A. Ball, Magazine Rifle Cordite Mark 1, used the same bullet but delivered 1970 feet per second at a chamber pressure of about 17.5 tons per square inch. Small changes to the bullet jacket resulted in the Mark II of both the black powder and cordite versions, the Mark 2 and Mark 2.C respectively.
Nitrocellulose was first used as a propellant in 1894, but the higher temperatures and chemical activity was enough to make it unsuitable for use in the Lee-Metford, and the newer Lee-Enfield was introduced to address these problems. Although not officially adopted until 1916, nitrocelulose rounds were widely used during World War I, although cordited-loaded rounds were still produced for use in the tropics, where it was considered to be somewhat more stable.
The round nose bullet was found to be less than satisfying in combat, notably when compared to the Dum Dum rounds issued in limited numbers in 1897 during the Chitral and Tirah expeditions of 1897/98 on the North West Frontier of India. This led to the introduction of the Cartridge S.A. Ball .303 inch Cordite Mark 3, basically the original 215 grain bullet with the jacketting "cut back" to expose the lead in the nose. Similar hollow point bullets were used in the Mark 4 and 5 rounds, the primary production versions. These soft nosed and hollow pointed bullets were later outlawed in the St Petersburg Declaration and the Hague Convention, and in 1903 they were withdrawn from active service and were afterwards to be used for target practice until stocks ran out. To replace them the Mark 6 round was introduced in 1904, uing a round nose bullet similar to the Mark 2 but with a thinner jacket. It was generally agreed to be unsatisfactory.
In 1905 Mauser changed bullet design completely with the introduction of their "spitzer" rounds, the first of the classic design now referred to universally as "bullet shaped". In addition to being pointed, the round was also much lighter in order to deliver a higher muzzle velocity. It was found that as velocity increased the bullets suddenly became much more deadly, an effect later explained by hydrostatic shock and cavitation when the round hit.
The British took the opportunity to replace their Mark 6 rounds with the new Mark 7, using a 174 grain pointed bullet that gave a muzzle velocity of 2440 feet per second. In fact the Mark 7 was considerably different than earlier designs, or the spitzer for that matter. In order to lower the weight they made the front 1/3rd of the interior of the bullet out of aluminium instead of lead. While similar weight savings could have been had by using a single lighter material, such as steel, the design was deliberate in order to make the bullet "tail heavy". When flying through air the stability of the bullet was marginal, but when it rapidly decellerated when hitting a target, the heavier lead base wanted to "swap ends", causing the bullet to tumble and greatly increase damage. The Mark 7 round remained the standard for the remainder of the .303 service life.
In 1938 the Mark 8 round was approved to obtain greater range from the Vickers_machine_gun. The primary change was the addition of a boat-tail and slightly more propellant, giving a muzzle velocity of 2550 feet per second and somewhat better ballistics. Chamber pressure was higher, at 20 - 21 tons per square inch, making it suitable for firing only from the machine gun.
Tracer, armour piercing and incendiary cartridges were introduced during 1915, and explosive bullets in 1916. These rounds were extensively developed over the years and saw several Mark numbers. The last tracer round introduced into British service was the G Mark 8 round in 1945, the last armour piercing round was the W Mark 1Z in 1945, and the last incendiary round was the B Mark 7 introduced in 1942. Explosive bullets were not produced in the UK after 1933 due to the relatively small amount of explosive that could be contained in the bullet limiting their effectiveness, their role being successfully fulfilled by the use of Mark 6 and 7 incendiary bullets.
In 1935 the .303 O Mark 1 Observing round was introduced for use in machine guns. The bullet to this round was designed to break up with a puff of smoke on impact with a target or the ground. The later Mark 6 and 7 incendiary rounds could also be used in this role if required.
During World War I British factories alone produced 7 billion rounds of .303 ammunition. Factories in other countries added greatly to this total.
Weapons chambered for .303 British
- Bren
- Lewis gun
- Lee-Enfield
- Vickers machine gun
- Browning machine gun (aircraft)
Specifications
- Maximum length:
- Case: 2.222 in (56.44 mm)
- Overall: 3.04 in (77.22 mm)
- Case trim length: 2.212 in (56.18 mm)
- Primer type: Large rifle.
- Boxer or Berdan primed cases may be encountered.
- Rim thickness: 0.064 in (1.63 mm)
- Rim diameter: 0.540 in (13.72 mm)
- Case capacity (water): 55.7 gr (3.61 g)
- SAAMI maximum pressure standard: 45,000 CUP / 49000 lbf/in² (338 MPa)
See also
External links
- African Hunter (http://www.cybertorpedo.com/africanhunter/classcart/303british_01.htm)
- Sniper Central (http://www.snipercentral.com/303.htm)
Categories: Pistol and rifle cartridges