Jeff Ovington

Well if you have a 7mm Rem Mag, a .280 Rem would probably just collect dust.. Both are .284 bullet diameter and both are very close in ballistics.
The .280 Rem is based on a 3006 necked to a .284 bullet. The 7mm Rem Mag is based on the the H&H case necked to a .284 bullet. The 300Win .338Win .264 Win and .7mm Rem are all examples that where develped from necking up and down the .375 and 300 H&H cases..
The 7mm Rem Mag has an edge, in performance, but no animal will tell when hit in the right spot. Both have very close to the same recoil which are both very manageable.. Believe it or not the 7mm Rem Mag cartridges are probably cheaper than the .280 Rem at least in my neck of the woods they are probably because of popularity..It's up to you, but they are almost identical in performance..I'd say step up to a .338 Win Mag for moose and bear if you can handle the recoil and place your shots properly, and use the
7mm Rem Mag for deer if you really want another caliber of rifle. But you have a rifle at the moment that is more than capable of killing any one of these animals over and over again.. You can't go wrong with a 7mm Rem Mag..It's one of the most versatile calibers a one person gun hunter can own..But .338 is the ideal bear and moose caliber if you are looking for another caliber of rifle to hunt with..