Buddy has a 338-378 and it is a pretty good shooter. They have a pretty lousy muzzle brake IMHO.
If you want a rifle that has that much power, it might be the way to go, I would probably be more inclined to get a 300 or 338 RUM with a heavier barrel.
I know some guys who are shooting 1/2 MOA at 1000 yds with 300 RUMS and 210 JLKs.
