Not a cartridge name, but internal barrel dimensions: Bore/ land diameter 7.6 mm = .299", groove diameter 7.85 mm = 309", rifling twist rate one turn in 250 mm = 10". According to the Mauser table in Jon Speed's "Mauser - Original Oberndorf Sporting Rifles", page 275, Mauser used such barrels for the .300 US = .30-06.