Good point Artificer
I cant comment on your experience . But with my own military training . We practice or pull for some time with nickels balanced on the barrels. untell such time as we could drop the bolt and the nickel stayed where placed . Myself I had one he77 of a time doing that with the 16 but little problem with the M 1 .
As I stated before standing off hand I can hit at 3X3 ft target at 300 more times then not . Rested , and in the prone position I wouldn’t think would not be an issue .
But again , its knowing the rifle and the load . Myself I shoot a lot . Some 25-30 + lbs of powder a year . We also shoot small targets . Like paper towel tubes with quarter size dots at 50 yards , off hand
3 men and 3 horses at 400 is a big target , shooting at them all as one, smacks against everything I ever learned .
I think its more then likely the shooter probably chose his target . but was as you stated , off on his windage .
Again though , did that mater . Nope because he probably new that he would have hit one of them .
We simply do not know . The case could very well have been that he was holding for windage and possible had Tartleton as the target . But as others who shoot long range here can attest . Shooting across an open field , creates its own difficulties. Especially with a slow moving RB . Even on a dead calm day . The changes in the thermals coming off the different colors of the ground play havoc.
As such . I would lend to believe that the drift may very well have been far more then what we think . Even though the ball made it effectively into such a large target ., we don’t know really how much compensation was originally applied .
AS such , what may seem like uncanny shooting . May well have been 3 ft or more off from the point of aim