Batman, there is data in the manual for the 180 Scirocco bullet for the 300 RUM. Powders used are Hodgdon - 1000,4350,4831 / Alliant - RL-19,RL-22,RL-25 / IMR - 4350,4831,7828.
If you have a powder prefrence let me know and I will post it for you. Best powder "load density" is with the H-1000 @ 100% case fill and RL-25 @ 96%.