The .257 Roberts is a great little gun for deer and goats. Congrats on your purchase. You will enjoy it.
I have always used the Nosler Partition bullets in my .257's with excellent success on both deer and antelope. The 100 & 115 gr. for antelope, and the 115-117 gr. for deer.
4350, 4831 and RL-19 powders have always worked the best for me. Either IMR or Hodgdon versions work well in the 4350 & 4831.
Stay with standard primers, and work up loads as pr all the manuals say.
Good shootin' and good luck. Gillette