I'm on my way ut to shoot a couple guns chambered in 270WSM right now , I'll post again in a while to let you know what I got.
I'll be shooting 130 and 140 gr bullets one BAR and one custom bolt gun
I like Retumbo and the 140grn AB. I don't have any data in front of me, and I wouldn't want to guess. Shoots .5" or less @ 100 with my factory pencil neck stick.
try Sierra 150 gr SBT in front of 66 gr of 7828 with CCI 250.
of course work up to it and see how it does on the pressure. Around here we use 100 - 115 gr .277 for varmints and 150's for hunting in standard twist rifles.