I have been getting good results with both R25 & R26 and a 140 grain bullet in my WSM these run right at 3,200 fps. The thing to keep in mind is the SAAMI pressure at 65.000 PSI is already red lined. It doesn't take much for pressures to exceed the comfort level at this pressure level.
One thing there is no need to push the 270 WSM as the 270 Winchester has been getting her done for decades, some of the Win. loads were only clocking 2,850 fps and they still worked.
