.577/450 Martini Henry ammunition, also known as 11.43 x 60R, is a round with British roots. Designed in 1871 for the single shot lever action Martini Henry rifle, the round has the distinction of being the last big bore, black powder round designed for military use with the British empire. The .577/450 Martini Henry served in several small brush wars, including the Anglo-Zulu War before being replaced by the 303 British round, a small bore cartridge.
The black powder round, like most rifles of the time, fired a very large round backed by a significant amount of black powder. The .577/450 Martini Henry used a 400 or 480 grain projectile at 1,450 feet per second and 1,350 feet per second respectfully. The .577/450 Martini Henry used 85 grains of black powder behind the projectile. While the round was replaced by the 303 British at the end of the 19th Century, it was used in World War I with a specialized incendiary round for spotting purposes.