Recently released RL-33 is slower than Retumbo but will make the heavier 25 cal bullets fly faster than RL-25 or Retumbo with excellent accuracy.
My 28" 3 groove is shooting moly coated 110s at 3675 fps with 83.5 gr of RL-33. Case is very full at this point.
Work up from 76 grs and see what your rifle likes. 76 gr was 3318 in my rig.
Thought I'd mention it as many of the other powders are hard to find. RL-33 pops up for sale and seems to linger longer before it too is sold. FYI Powder Valley has some right now (3/21)
http://www.powdervalleyinc.com/