Apparently, "Brown Bess" is a very old combination of slang terms, with "Brown" meaning common/everyday/plain, and "Bess" being a stereo typical peasant or commoner, woman' name, especially if that woman were involved in prostitution. Today though, over time some of the old slang has changed or lost meaning. For one example, "sluttish" today means a woman of "loose sexual morals" but a few centuries ago, it mean "slovenly", and didn't have the sexual connotation that it has today [I've been taught]. It's this loss of meaning that has caused some of the confusion, or theories that "brown" somehow was due to color, and "Bess" was somehow connected to Queen Elizabeth aka Queen Bess....,
So IF we used modern American slang back when the musket became the primary , we might call the Brown Bess musket something like, "plain Jane". Note how many of our former service members will remember during their service being taught how their rifle was their new "girlfriend", and to care for that rifle as good or better than a girlfriend.
Here is an article that I found that seems to give a good account of where the name stems for the British service musket(s) that span three centuries:
History of The Term Brown Bess
LD
So IF we used modern American slang back when the musket became the primary , we might call the Brown Bess musket something like, "plain Jane". Note how many of our former service members will remember during their service being taught how their rifle was their new "girlfriend", and to care for that rifle as good or better than a girlfriend.
Here is an article that I found that seems to give a good account of where the name stems for the British service musket(s) that span three centuries:
History of The Term Brown Bess
LD