Variables in velocity in load development for 270WSM

Range update: I think I've settled on a load for the 270WSM with 150g Accubonds. I kept my seating depth the same and just tried: Nosler, Win and Federal Brass along with WLRM, 9.5M and Fed 210M primers. On 2 different range sessions I got my best 2 groups with Federal nickel cases with Fed 210M primers: 0.313 last time and 0.352 today. The velocity was within 27FPS for the 2 different range sessions. Going to be my cow elk load for this fall. Maybe during the off season, I will play with the other primers I have but pretty happy with this load. Thanks for all the helpful comments.
That level of accuracy allows you to stretch your range waaaaaay out there!