I haven't, but I'm wondering: in a .375 H&H what is the advantage of a 350 grain TSX? With a TSX, more velocity is helpful in promoting expansion and penetration, and you're not going to get it in a .375 H&H with its somewhat limited powder capacity.
If one were hunting elephant, a 350 grain solid might be a good choice.
For lesser animals, a lighter weight TSX would seem to be better. My son and I used 270 grain TTSX last year for buffalo and eland and they worked great.
Just my thoughts, but I'm curious about why you want to use a 350 grain TSX. I can't answer the question about the twist.
