Heinz you mention your 'jaeger' being finished on all 8 flats. I am not sure what you are indicating insofar as your definition of "finished" but I have never, ever, seen an American rifle with anything more than very coarse filing marks on the underside of the barrel. Most that I have disassembled or worked-upon, and it is no inconsiderable number, have evidence of either very coarse filing (almost rasp-like) or grinding with intermittent hammer and forging marks/scale. European arms, on the other hand, many of which I have also disassembled, display a much more refined degree of finish work underneath; however, I have never seen anything underneath even remotely approaching the level of finish on the top three flats. This is not due to greater care in manufacture by the stockers, however; this is due to a much more defined system of work delineation, and barrel being supplied to stockers by people who did nothing 24/7 but finish out forged barrels. This type of system was completely lacking in America until after the Revolution, although it had its origins here during the Revolution with the hasty advent of more specialized factories for rapid production.
I also stand by my own comments that most American-stocked arms prior to the 19th century would be completely unacceptable by the standards applied here in 2020. I can likely count on one hand the number of rifles I have seen with full octagonal inletting of the barrel applied down the entire length of the forearm, and I can certainly count on one hand only the number of lock inlets that I've seen which employ a full bridle profile. Most, as I have put forth, are just large holes in the stock with a couple of extra reliefs to accommodate the bridle screw heads. I don't see this as "UNworkmanlike" at all, in fact, I see it as the definition of "workmanlike." I do not think the vast majority of American gunsmiths were anticipating that their work would last 100 years, if even that long, regardless of the cost. I firmly believe that the concept of minimal wood removal - even to the modern ridiculous extent of itty bitty sear spring pieces of wood left standing - would be beyond comical to an 18th century American stocker.
To those who like to leave little 'sear spring triangles:' wait until you're out in a drenching rain and then conspicuously wonder why your trigger pull will not fully release the sear! What a giant waste of time. I think an apprentice would have been beaten senseless.