This has happened a few times. Find a good load one year, go back the next and it isn't a great load anymore. BUT the loads I am working on now both in .260 and 7mm Rem Mag I got Great groupings with Low ES ....4 days ago. I load the exact same loads so I am shooting in the same location with the same weather, same everything that I can think of and the groupings have doubled in size. The velocity also changed. On the .260 Still have an ES of 12 but 28fps slower. On the 7 an ES from 7 is now 23 and velocity 16fps slower. Any Ideas of why? So frustrating. Thanks for any help.