I just received "Firearms of the Fur Trade", volume one in The Encyclopedia of Trade Goods by James Hanson. It has 583 pages and is hardcover and available through the Museum of the Fur Trade at
www.furtrade.org. This is a terrific work. Color photos are outstanding. If you are interested in French or English trade guns from 1750 onward, this is an amazing resource. There are some earlier pieces, Dutch guns, etc. but these of course are rare. Perhaps the most amazing to me is that the author found original, "as new" 18th century trade guns in a Swedish museum that show what these guns looked like new. They looked good. I've just begun to delve into the book and I'm sure it will be a source of enjoyment and knowledge for decades. The Northwest guns section is huge.
Hanson does not re-classify trade guns that Hamilton previously classified in an alphabet soup, but there are more color photos of each type than seen anywhere else and he summarizes features well. Importantly, he does give the weights of the guns in the book and they are shockingly light, some around 5 and a half pounds with long barrels (48" for example).