The British "Gunmakers" called this round [the Austrian 8x50R] the .500/320 Flanged Nitro Express. It was offered B.S.A.Co. manufactured, "Gunmaker" retailed Lee Speed type rifles after the 1907 ban on British rifle cartridges & their components in India & Africa.
While we always hear about the ban on .450 rifles, cartridges & components [because of the .577/450 Martini round], which spurred the development of the .465, .470, 475, .476, &c. cartridges, it also applied to the .303, as well as the .455 Webley.
A 244 grain bullet, with a Sectional Density of 0.322, cruising at ~2,000 fps, will do anything the old MK VI 215 grain bullet will out of a Lee Speed.