My 338's (5 of them) had, from the factory, 24 and 26" barrels. I cut 3 or 4 of them to 22".
Only my 24" rifles could get to 2,750 (2,735 actually) with ANY powder and a 250, including RL22. The 26" one's would tickle 2,800. And all of them got 250's run in them.
None of the 22" barrels would comfortably get past 2,700 with a 250 (they typically went 2,680) and any powder I used (H4350, H4831, RL19, RL22).
But maybe I didn't push hard enough past pressure tested velocities
2,850 with a 250 from a 24" barrel is pure hot-rodding fantasy and well outside the limits of RL22 and the 338 WM's SAAMI pressures.
You want more juice than the 338 WM, a 340 Wby or bigger is in order.
A 338 WM is just a 30-06 on steroids, and performs about the same velocity-wise with bullets of equal BC/SD.