A friend of mine let his son use a .260 on antelope and was very satisfied.
Don't remember the specifics of his loads, but the distance was over 200yds.
I have the Encore with .260 Rem. 15" TC factory barrel no brake etc. Using the Nosler 120 gr. bullets it is deadly on deer. My favorite load is
Nosler 120BT over 39.5 Gr of IMR 4895 with Rem. 9 1/2 primers. It chronographed @ just over 2500FPS last fall. Accuracy is +/- 1" @ 100yds. If you don't break a shoulder or the spine, you may have to track the animal while they bleed out. One large doe that I shot ran 77 yds after being shot through both lungs. I stay away from the shoulder as it ruins too much meat and it is a carry over from being a Bow Hunter.
With Reloader 19 you can get about the same accuracy & velocity, but with more recoil. It takes more Reloader to get the same velocity.
Good Luck, and keep us posted on your results.
Rol