My .375 Ruger is built on a JC Higgins M50(FN) action with a 21.5" McGowan barrel.
I've done some chronographing with the following results(all velocities are a three shot average):
Nosler 260 gr AB with RL15
72 gr - 2726 fps
74 gr - 2811 fps
76 gr - 2873 fps
pretty much the same velocities as the Nosler Manual. Interestingly, my best accuracy was with the 72 gr load - same as the Nosler results.
I've also done a bit of testing with the Hornady 270 gr SPIL and RL17. Alliant states that RL17 has a similar burn speed as IMR4350 so I started well below Hodgdon's minimum load for IMR4350 and worked up to just below Hodgdons maximum load.
75 gr - 2494 fps
76 gr - 2546 fps
77 gr - 2595 fps
78 gr - 2656 fps
79 gr - 2673 fps
80 gr - 2698 fps
81 gr - 2751 fps
82 gr - 2801 fps
