RE: 8mm Rem Mag versus .338 Win Mag
Good that you' re a handloader. Either will do the job as well as the other.
However you really got to ask why the .338 has outsold the 8MM Mag better than 500 to 1...( I' m guessing on the number) I personally have never seen a 8MM Mag and I spend a lot of time is gun shops.