So, this is a broad question without clear answers as far as I know. Rule #1 is to almost never use contemporary kit offerings as primary sources of information about originals. Period documentation can offer clues as far as barrel lengths, bore sizes, quality of locks, stock wood, and even furniture but nothing of architecture.
The timeframe and where the guns were supplied from would dictate architecture. French, English, Belgian, or American? When, between 1690 and 1850? Or where in between?
“Chief’s grade” can often serve as a marketing tool. Then and now, I guess.