.303 British (using Sierra bullets)
Date: Oct 18 2016
The .303 British was developed in 1887 and officially adopted in 1888 by the British Empire. Originally it was a black powder cartridge containing a 215-grain round nose bullet with a cupro-nickel jacket propelled with 70 grains of black powder for a reported 1,850 fps velocity. As new powders were developed, including cordite and double-base extruded powders, velocity was increased to around 1,970 fps. Eventually bullets were improved with a 175-grain spitzer being pushed to 2,440 fps, which was the standard issue military load until the cartridge was retired. The British used this cartridge for around 70 years that included two world wars and countless other engagements before replacing it in 1957 with 7.62 NATO. Its popularity around the world is widespread, and with many surplus rifles readily available, almost all major ammunition companies offer loads.
As is often the case with cartridges having such a long history, the groove diameter of rifles can vary. In developing the accompanying data, Sierra bullets measuring .311 inch were used. Excellent accuracy was achieved with an Enfield No. 4 MK1 with 174-grain MatchKing HPBT bullets. The 150- and 180-grain SPT bullets were also accurate and are preferred for hunting big game due to their reliable expansion.
Several loads were developed that more or less duplicate today’s factory loads that advertise a 180-grain bullet at 2,460 fps, with actual velocities being something less than that figure. Powders included IMR-4895, IMR-4064, IMR-4320 and Hodgdon H-380.
Many service rifles have been fired extensively and have excess headspace, which can cause accuracy loss and can even be dangerous. If it’s in question, have your rifle checked by a qualified gunsmith prior to firing it with any ammunition.
Maximum industry pressure guidelines for the .303 British are currently established at 49,000 psi, and none of the accompanying data exceeds that figure.