One problem with the WSM is load density with most bullets. If you took 71gr Retumbo and seated a 140gr AB you have pretty compress load for the 270WSM.
Hodgdon has max load of 71gr/Retumbo for the 270WSM with 140gr @ 3165fps and it's listed (C) compress same with H-1000.
I've tried H-1000,Mag-Pro,Magnum,R-22,R-19 with 140 and 150gr bullets in a custom 270WSM it had 26" long Lawton barrel.
I finally settled on R-17 for the 270WSM and 300WSM most bullets for the 270WSM your going to be seating the base of that bullet into the case body. Well good luck