I've been looking at getting one of these attached to my FNAR (since it's also a BAR, it should be compatible with a stock Browning unit if threaded properly). From all reports, it really does work (hard to believe, I know, since it certaintly
seems gimmicky to me). Hopefully some folks with first-hand experience can chime in to second this.
Here's some background info for folks who don't know what the BOSS brake/system does:
Basically, it gives a shooter/reloader one more knob to turn in the search for ultimate accuracy. Whether or not that knob has any effect (or is even needs adjustment) depends on how close to optimal accuracy you can get with the standard tricks (bedding, ammo, trigger control, doping, etc.). If you can control for all those other factors (yeah, right!) then it is unlikely accuracy could not be improved some more by playing with the tuning of the barrel harmonics (which is what the BOSS does). How far "off center" the rifle shoots from its "sweet spot" due to harmonics determines what (if any) effect the BOSS will have. In most cases, accuracy is definitely improved, but not by leaps and bounds. Merely an additional fine tune.
The primary benefit of the BOSS to the target shooter is that it is an effective brake, more than anything. I've been told they are extremely loud (may not be great for hunting, therefore, unless you have really good muffs/plugs). If the noise doesn't cause a flinch to develop, they can only help accuracy
The primary detriment (besides the noise) is that your system is "locked in" to one
very consistent loading to achieve best accuracy. But this is true with any gun (the "ideal" load), only with the BOSS you can change it. The adjustment numbers on the brake should make it easier to "re-zero" between different optimized load/rifle configurations, though. I can concieve that shooting a normally accurate load with the wrong BOSS setting could cause a nasty flier; bad when you only get a first shot. Just one more thing to keep track of.
TCB