I came across this excellent article, well worth the time it takes to read. This article covers the realities that lead to the creation of the famous Brown Bess, as well as the various models and design changes that occurred. The article has been out for some time but I didn't find it when searching the forum - apologies if I missed it and this is actually a repost.
https://www.americanrifleman.org/content/the-redcoats-brown-bess/