The Sierra 110 HP will work OK with Varget. If you get the smaller 110 HPs that are made for the 30 carbine or 30 caliber pistols, they will come appart on you. There might be other bullets out there that will work, but I have not tried them personnally.
I have used mag primers in my 7mm Mag and 338 Win Mag. Never needed them in any of my other rifle calibers and I am only missing a few between 22 hornet and 338.
I once took a rock chuck at 440 yards with a Savage 340 in .30-30. That little gun liked the Speer 110 HP and a dose of Reloader 7. First shot I held high and shot over it. Next shot I aimed at it and hit a little low. Last shot was top of back and nailed him dead center. My buddy and I counted the railroad joints from where I was shooting to where the chuck had been laying on the rock. Confirmed with my dad (track inspector for the railroad) that it was indeed 440 yards.
Those light bullets will shoot in some of the heavier calibers if you find the right load.
Good luck,
Steve