I had the same results my first couple of times out w/ this powder/cartridge combination. What I found (and experience since has confirmed) is that it burns much better with higher load densities.
If you use the "start" loads and work your way up but don't have good accuracy early on stick it out; it gets good the less open space there is in the case.
My rifle really likes 58 gr IMR-4350 under a 165 gr Sierra Game King HP, although it doesn't yeild as much velocity as RL-19 for me. Accuracy is definately good though.
