In a review of the BOSS equipped rifles when they hit the market over a decade ago, the people testing the rifles (in a variety of calibers) were not able to improve much on the Browning recommended settings per various bullet weights. (Perhaps experimenting with a quarter turn here and there for a given loading might help, but I'd not be surpised if their recommended setting performed best.)

That being said, their sample 7 mm Rem Mag A-Bolt was turning in .28" groups @100 yards with some ammo, so apparently, the rifle indeed has potential!

Good luck with it...take it to the range with a variety of factory loadings, and you might be able to find a factory load giving 1/2" groups!