WSM = Winchester Short Magnum. A variety of WSM cartridges
exist, i.e., 270 WSM, 300 WSM, 338 WSM BOSS = Ballistic Optimizing
Shooting System. It is a a 3.5-inch long combination muzzle
brake/weight. It threads onto the end of your barrel. By changing
its position along the threaded muzzle, you change the length of
the barrel and subsequent vibration/harmonics.