@Smokey Plainsman
I don't know that you'll find complete and definitive answers to all of your questions, but there is some documentation that will contribute to the discussion.
Regarding round balls or shot, they used both. Much of the discussion of shooting trade guns on this forum centers around ball loads, but native hunters evidently used a lot of shot, as well. This is from Caspar Whitney's
On Snow-Shoes to the Barren Grounds (1896), page 114:
View attachment 169853
I'm not sure his "30-bore" designation is quite right, but he was discussing the native Dogrib people of northwestern Canada, with whom he traveled. His reference to "ball in winter and shot in summer" is probably a reflection of the types of game that were hunted... Big game (e.g. moose, caribou, wood bison) in the winter and small game, birds, and waterfowl in the summer.
Isaac Cowie was a clerk for the Hudson's Bay Company starting in the 1860's. He was primarily based in Saskatchewan, and he wrote his memoirs as a book,
In the Company of Adventurers. Here he describes traveling between trading posts with a native family. One of the children was armed with a trade gun, and hunted small game as they went. In Cowie's own words:
View attachment 169854
Cowie described a substantial powder charge with a relatively light load of shot, but it was very effective in the long-barreled trade gun. Cowie was a knowledgeable shooter, who was very familiar with the firearms of his day. I would take him at his word.
Samuel and Gideon Pond were Christian missionaries to the Eastern Dakotas in Minnesota starting in 1834, until into the 1850's, I believe. Samuel Pond wrote up his observations of the native people in a book,
The Dakotas or Sioux in Minnesota As They Were In 1834. This book is remarkable for its sensitivity and sympathetic views of the Dakota people and their lifeways and spiritual views. Anyway, here are Samuel's comments on firearms:
"The men used smooth bore guns much more than rifles, and it was a considerable time after the percussion lock was introduced, before they learned to prefer it to flint. They manufactured shot from bar lead by melting and pouring it through a sieve of perforated bark held over water, the sieve being jarred while the lead was running, so that it fell into the water in drops" (p. 356).
So, not only did the Dakotas use shot, they actually made it themselves.
I've found less about specific loading techniques, but there is at least one quote regarding how the Cheyene Indians loaded their trade guns with ball rounds. This is from
The Life of George Bent, Written From His Letters, compiled by George E. Hyde:
View attachment 169890
George Bent was the son of William Bent, one of the founders of Bent's Fort, and Owl Woman, who was Cheyenne. Since the Cheyenne people were matrilineal, tracing their ancestry through the mother's lineage, George was himself Cheyenne, and he lived much of his life with his mother's people.
Regarding ball loads for trade guns, there is a lot of information out there, but I don't know that it is collected in any one place in a format that is useful to shooters like us. From what I have gleaned from reading, the typical "trade ball" was 28 gauge, which would be .550" diameter. Many of the traders stocked a few other sizes in addition, but this seems to be the most commonly available. This comment from the Earl of Southesk, who traveled across the Canadian plains and wrote of his experiences in
Saskatchewan and the Rocky Mountains: A Diary of Travel, Sport, and Adventure, During a Journey Through the Hudson’s Bay Company Territories in 1859 and 1860, seems to support that:
“My men had various guns and rifles of their own; none were worth much, except a highly-serviceable double-barreled gun belonging to M’Kay, of the best possible pattern for general use in that country. It was as thick in the metal as a rifle, and carried a bullet accurately to more than a hundred yards, and as its bore was of the size (28) universal in the company’s trade, supplies of ball could be got anywhere and almost from any person. Small as these bullets are – for being round, they had none of the expansion of a conical ball, especially a flanged one such as that shot by my rifles, which were really but little different in the gauge – they are large enough, if well directed, to kill any beast in America; stores of them, moreover, can be carried in little bulk – an inestimable advantage for the ordinary hunter.
“This handy and neatly-finished gun, which was made in London at a trifling cost (₤12 if I rightly remember) could also throw shot with a power that I have never seen equalled [sic]
. Good as my Purdey smooth-bores were, M’Kay used to kill ducks at distances fairly beyond my range” (p.38)
In
Small Arms and Ammunition in the United States Service, author Lewis stated that military smoothbores in the 18th and 19th centuries were typically loaded with balls 0.050" under bore size. Most (but not all) old Northwest guns now in existence seem to run about .60 caliber, so a .550" ball would have probably been about right. This seems egregiously undersized to us modern folk, to the point that some may not believe it is true, but the documentation and the artifacts (actual balls, and gang moulds) are there.
The Earl of Southesk also presented a trade gun to one of his men, and described the fellow's efforts to get it to shoot to his satisfaction:
View attachment 169892
So, that ought to get you started, if you are really interested in period correct loads for your new trade gun. Good luck with it!
Best regards,
Notchy Bob