Basically the same thing as the .30/.338 Winchester Magnum, a wildcat catridge used for 1000 yard shooting.
Google it, and you will find lots of information.
Do you have a .308 Norma Mag, or do you want to buy one?
Just my .02,
LeonCarr
As Leon Said, just about identical to the .30-338WinMag (a wildcat cartridge) which is probably just as easy to load for as it is to find .308 Norma Mag ammo at a reasonable price.
For some reason or another the cartridge (30-338) seems to be much more efficient than the .300 WinMag.
When I had a 30-338 my most accurate load was 180 grain Nosler Partitions leaving the muzzle at 3120fps. It was great for killing mule deer and elk.