BOSS

Pooh,
The BOSS system is a Browning design and I do believe under license it was offered on Winchester rifles I would have to research that further. Here is a link from Browning on the BOSS system. 

www.browning.com/support/frequently-asked-questions/boss-system.html  After looking at Browning's web site they offer their BAR MarkII Safari with this system on that rifle. Most of the rifles that had this system was in the muzzle brake variety but as you look over the link you'll see they had two varients. With the muzzle brake ones the only con was the increase in the muzzle blast. As you'll see in the link it was helpful with barrel harmonics. With barrel harmonics some  of your target shooters use a outside weight on the barrel that they adjust to help in this.