Gotcha, thank you."cosmic"The term BB originated from the nomenclature of the size of steel shots used in a shotgun. Size "BB" shots were normally 0.180 in (4.6 mm), but tended to vary considerably in size due to the loose tolerances in shotgun shells. The highest size shotgun pellet commonly used was named OO or double ought and was used for hunting deer and thus called buckshot, while the smaller BB-sized shot was typically used to shoot small/medium-sized birds and therefore was a birdshot.
Given that I own a couple of shotguns, which I obviously never shoot, I’m kind embarrassed that was not instinctive knowledge."cosmic"Yes it is a throw back to the begining of shot manufacturing.. It is the designation of the size of the projectiles..