This is an older video that explains it very well.
Browning Boss SystemAs others have mentioned, if you hand load, then don't use their sweet spot. Pick the middle setting and tune your load to this setting. This allows you to have adjustment on both ends of spectrum. I have been shooting a Medallion 7mag A-Bolt II since about 1994 when I got it as a kid. Wasn't until just recently I picked it up and started shooting my Tikka. Now that I reload, I plan on pulling it back out and setting it up strictly for long range. I'll tune the load to the setting of my choice then dial it in any closer if I can.
If you have ever taken it completely off, there is a plastic type strip that gives resistance to the adjustment brake section. I lost mine prob 15 years ago. Weedeater string works perfect and fits perfect in the small groove that it lays in. telling you this because it you pull it off to clean the brake, keep an eye on that strip.
Also, the "sweet spot" settings that Browning lists, do not list most of the newer high BC bullets. So as BSA mentioned, if your shooting factory ammo and it isn't listed, then find the closest one and use the method in the video or do this:
1) Put setting at 0, fire 2 shots
2) Put setting at 1, fire 2 shots, if shots open up, dial back tenths to fine tune. If shots group closer, turn to 3.
3) While n setting 3, fire 2 shots, repeat process until desired groups are found.
Also, if your not interested in the brake and the recoil is ok with you, get the CR tuner. CR (Conventional Recoil) tuner is the same as the radial brake, just not near as loud. However you will get all of the recoil like a normal rifle. In 1994 I inquired about it and Browning gave me one for free. So I have both. Not sure if they still do that or not, however it can be purchased. If you do indeed look for one, let me know, my CR case has a list of the model numbers on the back of it from 223 to 375 caliber.
Oh and at the time, people thought it was the ugliest thing that they had ever seen. Now pro shooters like Eric Cortina sell their version of their "barrel tuner" (BOSS) to the public so load can be tuned to their setup.