I have tried H4350, R17, and VV160 in my 260, some were really good, but not great. I went thru 300 rnds of H4350 trying to get better groups, but it never happened...best was 3/4 moa with 43.2 gr and a 123 scenar.
Then i tried Varget, and it was by far the best powder for my rifle....very very good groups near and far with minimal vertical... It is actually quite popular with the 260 crowd.
I shot 140/142's, 130/129's, and 120/123's with Varget - match and hunting - i went with Dan Newberry's recommended OCW loads, started lower and worked up - and what I found was all three bullet weights settled in their node within 0.3 gr of what he listed as OCW Varget loads.