There were a lot of “sightless” trade guns in native hands. I’m using a mobile device right now and I’m unable to post links or pictures, but there are a lot of them out there.
Maybe sometimes the sight got knocked off, as yours did, or the barrel may have been shortened and the front sight was simply not replaced. One apparent contradiction to this is in R. Stephen Dorsey’s “Guns of the Western Indian War,” in which he describes guns confiscated from the natives. Many of these arms had been shortened and Dorsey made a point of mentioning that most of these had some sort of replacement front sight installed, so the Indians must have appreciated the advantage. I have also seen several mentions of native shooting technique, which utilized a rest of some sort, either a natural feature, a wiping stick used as a monopod, or crossed “gun sticks.” However, most of these references deal with a period later in the 19th century than is of interest to many folks here.
The Earl of Southesk also documented one of his (Metis) men working on a new trade gun to get it shooting to his point of aim. This involved bending (or straightening?) the barrel in between the spokes of a wagon wheel. The point being that these men understood the importance of careful and deliberate aiming.
However, we still have those old guns without front sights. I own one. Mine is an 1864 Springfield that had the barrel cut back to about 24”, obviously with a three-cornered file. The stock was cut just ahead of where the middle barrel band would be, although the band is missing. There is a missing splinter of wood from the right side of the forearm, but the patina indicates this is a very old break. There are no tacks or rawhide repairs, but I am confident this gun spent some time in native hands, and it has obviously been shot a lot.
In my opinion, shooting muzzleloaders is like shooting archery in some respects. Shooting a rifle with fine sights and double set triggers can enable some very precise shooting. Much like shooting a compound bow with a front sight, string peep, and mechanical release. When I was shooting competitive archery ~30 or so years ago, eighty yard targets didn’t faze me with a setup like that. Shooting “barebow,” you don’t have sights, but you use other techniques to enable precision shooting. Instinctive shooting is a third and whole different method… you focus on the target and “become the arrow.” I have seen some fine shooting done by instinctive archers at reasonable distances. I think the main or possibly only limitation is range, although as with almost anything else, you can improve with practice. Native hunters, I believe, were probably pretty good at getting up close when hunting game, and they may have very well used instinctive techniques in shooting their “sightless” guns.
I would encourage you to experiment, maybe working out some “bare gun” sighting techniques as well as pure instinctive shooting. I would be interested in what you find.
Best regards,
Notchy Bob