I bought one of the rem mtn rifles when they first came out,later bought a ruger ss,later sold the 2 to buy a rem bdl with 24 in barrel.All have been exceptional shooters,the first one I bought a box of rem cor-loc 140 to get the brass to reload.The core-loc was very accurate took deer with it the first year.Took deer with the 100 gr (hand loads) 120,and 140,most dropped where they stood others didn't make it 25 yds.Took one last year at 442 yds with a 120 grain bullet,it went about 12 ft.
If you are going to use factory I would try the core-loc 140.If you are going to hand load I would try a 120 BT,Speer 120,or sie BTHP 120 useing R-19 47.5 grs Or IMR 4064 42 grainsrem 9 1/2primers.Would start lower and work up with the 4064 most loading book just go to 39 grs.R-19 goes up to 48 grs as max.