I've had excellent results using 26.0gr Varget under 50gr Nosler BT's, and tentatively (still narrowing down this load) 25.5gr Varget under a 55gr Sierra SBT; CCI primers for both. One issue I did notice is that my Ultra prefers loads at or slightly under 2.245" COL. The Winchester white box & Ultramax factory loads are shorter than this, and when I loaded longer than the above, I noticed my groups opening up somewhat. So far, both of these handloads shoot .6" - .8" at 100yds pretty consistently.
One other note, the Handi's will start to stick cases sometimes when you shoot hot loads; the good thing is, as with most loads, the fastest isn't always the most accurate.
Good luck! :grin: