Lee,
I shoot both the 270 gr. TSX and the 250 gr. TTSX out of my .375 Ruger. MV of the 270 gr. load is 2800 fps, and 2880 fps for the TTSX. I could push the TTSX faster, but it is very accurate- maybe a tad better than the TSX.
I wouldn't hesitate to try those 250 grainers. You shouldn't have any problems getting them to 2800 fps out of your .375, and may find out as I did that they are every bit as accurate. Plus, a better BC to boot.
I use Ramshot Big Game powder for the 270 gr. load, and H414 for the 250 gr. load.
