338 Dude, I had another 338 Ultra built using RL23 and 225 TTSX. This time I used 90 grs with RL23. 3135 FPS. My ES is single digits. At the time there was no data for this combo. I called Alliant after I did the load and he said try, RL 26 for the 225's and would get more velocity. It's shoots so good that I have not tried RL 26. I killed a bull at 400 yds and it worked!