Sweatty,
I use 52 Sierra 52 gr HPBT's & 53 Gr Sierra MK's being pushed by 34.9 gr of RE15. I get extremely good accuracy out of my Ruger M77 22-250. I've tried several powders and none match the consistency in accuracy and group size which is under 1/2" for a three shot group EASILY! Looking in the Sierra manual under 45 gr SPT bullets, there is a long list of powders available. For RE15, starting is 34.0 and Max load is 36.7. And BTW, I've tested loading to SAMMI spec and also loaded with .002 into the lands in MY 22-250. Believe it or not, SAMMI spec produce a tighter group despite the fact I have an .080 jump. Hope that helps.