Brits, you might be interested in a bit from an 1822 book, "An Excursion through the United States and Canada, during the Years 1822-3 by an English Gentleman". It's by Wm. Blane, an experienced English shooter and hunter who spent a couple of years along the Ohio River, hunting with and spending time with backwoodsmen. I believe he is describing his experiences in what would become Illinois in this bit, and with the rifles used in that area.
" In traveling through these Prairies, every one must be struck with the vast number of a species of grouse called “Prairie Fowls”. These very much resemble the Scotch grouse, both in colour, and in being feathered to the feet; but are somewhat larger. They differ however, in this particular, viz. that when disturbed, they will settle upon a fence or tree, if any be near. They are delicious eating, and are killed in great numbers by the unrivalled marksmen of this country. After driving up a flock of these birds, the hunter advances within fifteen or twenty paces, raises his long heavy rifle, and rarely misses striking the bird on the head. I have witnessed over and over again this surprising accuracy, and have fired away numberless pounds of lead in trying to imitate it, but without success. I contented myself therefore with shooting the birds in the body, by which I rather tore and spoilt them. But, however difficult I found it to hit a bird anywhere with a single ball, the Backwoodsmen regarded my unsportsmanlike shooting with as much contempt, as one of our country squires feels, when a cockney shoots at a covey of partridges on the ground."
Spence