Roundoak,
In th past H414 was always the best powder for me in my 7x57s. Recently, prior to a hunt, I tried Reloader 15. This load was extrapalated from a 7mm-08 and worked up. But the Reloader 15 is by far the most accurate powder for me in my tang safety Ruger. Now I did give up 100fps to H414, but for accuracy the R15 was the best. This powder actually has a burning rate close to IMR4320. Good luck.
