I know this is an old thread. but my new favorite powder for my AR15 is AA2520. I taken to slinging heavy metal at critters now. 75 grain Hornady BTHP over 25.2 grains of AA2520 is may new favorite coyote load. If I'm hunting pigs I swap in the 75g grain Swift Scirroco II over the same load.
I am using the 65 sgk with 24 grs ot Ramshot Xterminator . You might try a mag primer with your Varget before you change powders. sometimes it is something simple.
When I started looking for a load for that bullet I tried 25.5 gr. of TAC (sierra's suggested hunting load) and it shot so well I did not even try anything else! Give it a shot