The 303 British (designated as the 303 British by the C.I.P. and SAAMI) or 7.7×56mmR is a .303-inch (7.7 mm) caliber (with the bore diameter measured between the lands as is common practice in Europe) rimmed rifle cartridge.
Is .303 British still made? 303 British, remains in non-stop production today, though primarily as hunting fodder. Inducted into military service in 1888, the British had developed their black powder.