Is either enough gun for elk at 500 yards with a barnes 115?
500 is probably stretching it - there are certainly better choices for that range. I'm much more comfortable at 400 with my .257 +P, which pushes a 115g TSX to just under 3000fps when seated long. (My rifle has a lot of freebore, too.) After 400 the velocity drops below 2200fps and I've always been concerned about TSX's opening reliably at lower velocities, which is why I use TTSX instead.
When elk hunting with the Roberts I push a 120g A-Frame to just shy of 2950fps. I don't worry about whether or not they will open and if they can't do the job I don't have any business taking the shot. Even with the A-Frames 400 is near the edge of what I will take and I'd want a broadside.
If intent on 500 yard shots, I'd definitely prefer a .25-06. Better yet a .270, .280 or 7mm RM.