The gunmakers of the 18Th century were not unlike the professional gunmakers of today.
They never had one fixed pattern for the most part. When a customer came to them and ordered a gun the customer had his own specs the same as now. I suspect that most of them had a few finished guns on hand for sale made to what they thought were the most desired type just as some of us do now. To think that each gunmaker had one exact pattern he always made to me is an error in perception of what is [HC]. Kits are made to what the makers think is the most desired pattern for the market. They are semi mass production. If you want exactly what you want you must either make it from scratch or have someone else do so. In conclusion anything Haynes made or any other gunmaker of the period is HC.
Jerry,
I certainly agree with you that for the most part gun makers didn't have one fixed pattern. Just one place that is illustrated is in the large variations in the guns produced by the Hawken brothers. I recently saw an original Beck rifle that was typical Beck from the wrist forward but had a very non typical buttstock as was probably requested by his client.
I didn't suggest that Haines, or any gun maker, made cookie cutter guns as is shown by his guns in RCA. Quite the opposite, I'm pointing out the kit and barrel makers of today give that impression by most of them making 38 inch barrels the de-facto barrel length for an Isaac Haines gun.
Of course anything made in any given period is historically correct for that period. For clarity, I probably should have said that based on surviving examples of Haines' guns, barrels longer than 38 inches would seem to be more representative.
Certainly kit, barrel, and parts makers need to make products that ring the cash register to stay in business; it's unfortunate that so many of their products aren't more representative of what they're billed to be. That's just my view of the matter and anyone is welcome to disagree.