I don't use a break on my RUM either, but found a mercury recoil suppressor in the butstock helped me get back on target a little bit quicker. If you are looking to upgrade to a thumbhole stock the HS Precision pro hunter thumbhole has been a good stock for me. I glass bedded the original stock and it helped tighten the groupings, and the HS stock is shooting better without the glass bedding. I will probably bed the stock when I rebarrel.
The factory trigger on my 700 CDL was very inconsistant for trigger pull and I upgraded to a rifle basix. This was an easy upgrade and again, found to be helpful in shrinking the groups.
Good luck with your new rig. I have loved my RUM since I bought it and enjoy being able to tinker with it as I have funds.
"I am a stone. I do not move. Very slowly, I put snow in my mouth and he won't see my breath. I take my time. . . I have only one bullet. I aim at his eye. Very gently, my finger presses on the trigger. I do not tremble. I have no fear"