TNrifleman
Congrats on your new Ruger in .257 Roberts. I picked one up two years ago this coming January and it has become my favorite bolt gun. Mine was also used, a 1989 tang safety model that was still so new that there were no marks in the bluing under the safety. (I fixed that in a hurry!) It came with a Leupold M8 4x but more recently I bought a used Leupold Vari-X III 4.5-14x for it.
As to bullets and powders for deer hunting...
So far all Ive hunted is prairie dogs and coyotes. I had hoped to get a 120g A-Frame load worked up in time to take it deer/elk hunting this fall but didnt make it.
Heres what shoots well in my rifle:
WW +P brass
CCI 250 primer
75g Hornady V-MAX, COL 2.803, 46.0g H4895, 3609fps
115g Barnes TSX, COL 2.803, 48.0g H4831SC, 2958fps
115g Barnes TSX, COL 2.803, 44.5g H4350, 3013fps
120g Speer Grand Slam, COL 2.896, 46.0g H4831SC, 2904fps
120g Nosler Partition, COL 2.821, 46.5g H4831SC, 2899fps
120g Swift A-Frame, COL
, 47.5g H4831SC, 2947fps
Approach these loads cautiously if you use this data as most are top loads in my rifle.