Several years ago, I had SSK craft up a 257 Ackley Improved 15? Encore barrel with the arrestor brake for dual use (coyote & deer). At that time, I chose 100gr Sierra Pro-Hunters at 2880fs (balance of velocity and accuracy which is outstanding). I have taken three deer with this setup but no coyotes. Recoil is minimal, if I were to do it over, I'd go with SSK fish-gill brake over the arrestor I like it much better.
Dies are generally available; you can make the brass out of any 06-family case or the parent 7x57 Mauser to include the 6mm/244 Remington or 257 Roberts.
As for ballistics:
Hornady 75gr Vmax - 3200fs
Nosler 85gr BT - 3100fs
Sierra 90gr HP GK - 3100fs
Sierra 100gr PH - 2900fs

I have not tried anything heavier than 100gr bullets.

D