I have not yet tried the 210 TTSX Barnes bullet in my Ruger 338 WM. But I have shot the 210 Nosler Partition.
A couple summers ago I decided to find a load for the 338 using either Barnes 185 TSX or the old 200 X Bullets that I have.
I decided to try both bullets at the same time, one loaded with Reloder 17 and the other with Hodgdon Hybrid 100V.
Both shot under an inch with either powder in testing. I decided I liked the 200 gran with Hybrid 100V. I then upped the charge another grain and it shot as well or better.
Nosler load data for 210 Partition and Reloder 19 was the most accurate powder tested. If I were in your shoes I would load the Reloder 19 and the H3450 with three rounds each.
Starting load for Nosler was 72.0 grains, max was 76.0 grains of Reloder 19 at 3020 fps in their testing.
Hodgdon listed 70.0 grains of H4350 as max with a 210 grain bullet. Shoot both powders and then pick the one with the smallest 3 shot group and go from there.