RE: Browning "BOSS"...good, bad or indifferent?
Worth the $$$. No matter how expensive of a barrel you have, there will be some ammo it likes and some it doesn't . The BOSS makes it equal and lets you pick the ammo for the task instead of the barrel picking it for you.
They make a non-brake version too so noise isn't increased.
Tuning can get expensive ammo wise. Once you have a setting and ammo, be sure to write down the settings. And if you don't reload, buy a quantity of the same lot number of ammo you have tuned for so you have it already on hand.
I handload and use the same 2 loads all the time so it is an easy readjustment.