My .257 Roberts is my favorite rifle and has taken a lot of antelope with Barnes 100g TTSX and Nosler 110g AB. Daughters and nephews love it as well and have used it to take antelope. The .257 Roberts was gently used when I acquired it in 2004 and has served very well.
These days I would purchase a 6.5CM instead and without a second thought as it has similar recoil to my +P Roberts loads with better downrange ballistics. It is an excellent choice for your son and antelope. As has been pointed out above, it is also good for deer and elk at typical ranges.
Coyote Hunter - NRA Patriot Life, NRA Whittington Center Life, GOA, DAD - and I VOTE!
No, I'm not a Ruger bigot - just an unabashed fan of their revolvers, M77's and #1's.
A good .30-06 is a 99% solution.
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