My powder of choice for both the 260 and the 270 is Reloader #19.Accuracy is excellent in both calibers.IMR 4350 is also a good choice in the 270.I have got a little better velocity with Reloader 22,but the accuracy is better with Reloader 19.My 260 is a Ruger 77 and my 270,s are a Ruger 77 and a Ruger #1.