I have gotten 3230 fps out of the 200 gr bullet Nosler. I using W 760 powder with fed 210 primer in a Ruger Mark 11 with a 24" barrel. The load was develop in early 2000 in hot weather. The powder is subject to Temperature change. I have never done any more testing. The powder load is 75.5 grs. I did a latter test with single loads in my sons Browning action. Achieved the same powder load, but didn't chronograph the loads. Next step. Primers are flat, but no ejections marks. Different rifles will do different thing so use causation. Being the 338 loads are in the 70 gr area. I stepped up at .5 grs per case, and started at 70grs. I looked over each case as we fired them for pressure signs.
Someday I will get my new 338 W. M. with a 26" barrel, and really go back into load development. I generally use faster powders like H4350 and H4831 powders. Hadn't been able to get H1000 powders. and wasn't interest in until now. Good luck finding any presently.
That's the only round I use W 760 powder in. I am and "H" man for powder mostly.