Don't know much about the 280, but I have a remington 700 mountain rifle ina 35 whelen, and it's a perfect factory rifle for elk... light weight, accurate and aesthetically good looking. Good buy, and good luck on finding a good load. I'd hit up the AR forum for loads if yu can't find help here.
I have the same rifle in .280 and have used it on elk. I killed one elk with it before I got my .338 WinMag. I can tell you what NOT to use. Don't use Winchester Supreme Silvertips. They were around 160g. These were different than the Ballistic Silvertips that are out there now. All I found was fragments. It was at point blank range, but still shouldn't disintegrate. Elk was still dead but I wouldn't take a chance with them again. I have also used Winchester Failsafes on mule deer. They punch through but don't expand as much as I'd like. My recommendation is to stay with the heavy-for-caliber bullets...around 160g. Good heavy construction. I like Nosler Partitions but there are plenty of good bullets out there. I have heard Barnes makes a good bullet but don't have any first hand experience with them. I took a quick look through Cabela's ammo selection and sadly, there are not a lot of heavy game rounds available for the .280. Most of what's available are 140g and 150g deer rounds. It's a shame Remington doesn't sell a .280 in their Safari grade line. It would have a Swift A-frame bullet which would be fine for elk. The 700 Mtn Rifle is a great gun for elk hunting. Easy to carry and handy. Good luck with it.
One of the things I struggle with when afield is keeping my rifle clean and in good working order. Small amounts of dust and dirt collect moisture; moisture can freeze rendering your action immovable when you need it most. I have seen this happen on multiple occasions, and over time, I’ve learned the cause and how to prevent this from happening.
The first thing that you need to avoid before going afield is leaving excess oil on the gun. Oil will trap dirt and sand in all the wrong places....