I have some experience with RL33 and 180 CEB's in the 300 RUM. I got about the same velocity pressure testing with RL33 as I did with Retumbo with the 180's which was over 3400 in a 27" tube. 33 will be a little on the slow side for 190's in the RUM and it does best with the heaviest offerings like the 230 Hybrid where it will greatly out run Retumbo.
If you are talking about Berger 190's for hunting out of the RUM, I would strongly recommend against it unless you keep the MV down to around 3000 fps. My minimum weight would be the 215 Hybrid and prefer the 230 Hybrid. For high velocity frangible bullets, the heavier for cal are the way to go. More mass on target at lower velocity = good results.
