Pretty much this. I have a 26" Savage prefit barrel that's a straight taper down to .840" at the muzzle. Balance point is about mid point of the second M-lok slot from the baricade stop. My former Tikkas, 24" factory varmint balanced at the baricade stop and the 20" CTR was a bit rear heavy, balancing right in from of the mag. This is all with a spigot and Atlas CAL/PSR on the front. As pointed out by Lefty as well, KRG offers weighted accessories now to balance out the rifle as required.I think it'll take a 1.25. The problem from what I've heard is that the balance goes too far forward.
Copied from Bravo page.
Barrel contours accepted: 1.25" for 4" in front of action face, then 1.20" straight to end of forend. A 1.25" straight cylinder barrel will fit but we feel that the clearance is too minimal. We recommend using no larger than a varmint contour to keep proper balance.