an ultra fast burning powder
Wonder what powder that is. Never heard that one before. The 270win and 270WSM use bascially the same powder, with the WSM utilizing powder more on the slow side. In other words I couldn't see using 4064 in a WSM. Comparing the WSM and 270, I find the 270WSM kicking much harder out of almost identical winchester feather. But I use a 47gr IMR4064 load for the 270win and Re22 for the 270WSM.