I no shoota da .260, but I've found Re16 to be a very good replacement for H4350 in .30-06 and by all accounts IMR4451 is right there too. One of the sleeper powders for the .30-06 is Ramshot Hunter---according to some who have tried it. One of the great things about Hunter is the way it meters. QL suggests it would work well in the .260 shooting 140s.
I'm here to give and receive knowledge, not affirmation or adoration. If you don't like it, mierda dura
. Intellectual honesty is not for fragile egos.