As already stated, it all depends on the bullet chosen and the velocity it's achieving.
I run my 26" barrelled 338 with 225gr AB's at a velocity of 2900fps, it has an effective range of 800yrds with this combo, but it still depends on the size of the animal hunted as to whether this should be shortened.
This combo retains 1746fps and 1522ft/lbs @ 800yrds, adequate for most deer sized game, excluding Elk and Moose. Even though these figures are probably adequate for either, I wouldn't take the shot at that range.
I would limit myself to 600yrds on such game as the figures at that range are 2002fps and 2003ft/lbs.
It's all relative to what you're trying to achieve.