When helping guys in the shop determine caliber, we typically will print out some ballistic charts out to 1k to show performance of the different calibers. Realistically, a 7mm with a 180 Berger will have the same drift and drop as a 300RUM running a 210 out to 1K. The 300 will have more energy, but not by much. For most, the 7RM or 300WM is all they will really every need. Once you get past 1k for critters, the 338's shine with the extra energy they product. BUT, for most people, shots will be inside of 500yds and a "shootable" rifle is what is more important. Honestly, for most, a 6.5-284 or 6.5-06AI would be all they really need to make clean ethical shots on everything we have to offer.
This isn't to say the 300RUM is a bad cartridge. It is a great cartridge and is very accurate when build correctly. For some, even with a brake, its to much and they can never shoot them well. My suggestion would be either the 7RM or 300WM and run the heavier bullets in them. Put a good optic on the rifle and shoot lots of critters.
