The 30-338 is a 1000 yard target cartridge ,so close the the .308 Norma Magnum that the data is interchangeable.I use .338 brass for my .308 Norma mag and the end result is slightly shorter necks til they stretch out .Like using 30-06 brass to make .270 The 300Win Mag has a very short neck while the 30-338 and .308 NM has a longer neck ballistics are all very close.....................Reinventing the wheel and the .308 NM wasmade first! Harold