Hi Jim;
I have used 100 grain Hornady Interlocks, 100 grain Nosler BT's, and Sierra 85 grain HPBT bullets in my Browning A-Bolt Hunter 243.
I got the best accuracy with IMR4350 in my rifle for all three of these bullets.
For the Hornadys I did the best with 37.0 grains, and I got the best groups with 40.0 grains of IMR4350 with the Nosler 100 grain and the Sierra 85 grain bullets.
I couldn't get the Varget to do nearly as well as the IMR4350.
Jerry.