That's good news, since I purchased 4 boxes of just that loading. I'm new to the .257 Bob & really am enjoying this rifle. I'll soon start reloading with the +P Hornady brass & see what this cartridge can really do. Thanks so much.
3D
The answer is the Ruger action on your rifle is the same one they barrel for 52,000 CUP, 54,000 CUP and 63,000+ PSI loads. No need to worry about 50,000 CUP 2257 Roberts +P loads.
Congrats on your new rifle! Got mine (standard 22 M77R) a couple years ago and it has become my favorite bolt gun. Heres what min does:
3609fps = 75g V-MAX and H4895
3163fps = 110g Accubond and H4350
2958fps = 115g TSX and H4831SC
3013fps = 115g TSX and H4350
2899fps = 120g Grand Slam and H4831SC
2904fps = 120g Partition and H4831SC
2947fps = 120g A-Frame and H4831SC
All loads with WW +P brass and CCI 250 primers.
Several weeks ago the 75g V-Max load put 3 shots into a group measuring 0.232 center-to-center at 100 yards. And a couple weeks ago I took a coyote with this load at 479 lasered yards. The Roberts has a lot of can do.
Have fun!