Nice. He says that one is a .50 caliber smoothbore. Unusually small caliber for a trade gun.
I have the Wilson Chief's Trade Gun made by Caywood. It is of an earlier time period, being about 1740-50's. Mine is a .62 caliber (20 gage) smoothbore, and has a barrel about 6 inches longer than the NW Trade Gun. Also, no rear sight, like a shotgun, which is basically what it is. .
I use a patched .60 lead round ball of about 320 grains over 70 grains of 3F black powder as my big game hunting load. I have taken several deer with it. I am confident with it out to about 5o yards, but much beyond that the groups open up too much to be reliable. My last deer taken with this gun was only about a 20 yard shot. (archery range)
You can get some of these guns with a built-in jug choke, but most are cylinder bore. For small game I still load with 70 grains of 3F black powder, but then an equal volume of shot. (note; that is equal volume, not weight of shot). I like #6 shot for most small game, but go up to #5 for turkey. Not having a choke, my shot pattern expands rapidly, therefore I keep my shots at small game at under 30 yards, preferably around 20 yards.
I like to use 3F powder since I don't use a primer for my flintlocks, but rather I load and prime both from the same powder horn. 3F works fine for a priming powder. No need to carry a primer. But, if you load with 2F, then I would probably use a primer with 3F or 4F.
I experimented with buck and ball, loading my regular .60 round ball with 2 or 3 .50 caliber round balls on top of it. They flew every which way! I can see where buck and ball could be an effective load when used against massed troops standing in a battle line when you didn't care what you hit, just so long as you hit something. What you hit might be 2 soldiers down the line from the one you were aiming at. However, for a hunting load - forget it!
Lots of fun.
Been reading up on the SkyChief load method. Tried it today. 70grs 2f Goex, 1 nitro card, 1.125oz shot, 1 over shot card, 1 wet with canola oil cushion wad. Patterns at 25 yards were darn near perfect! Every pellet was inside a 30" circle. Very even with NO holes. My .62 Cal (19 guage) Pedersoli...
I tried 3fg powder today. Results from 80 and 90gr charges. Ignition was dang near instant! I filed down the front sight about .005" today and hope that will put it at least dead on at 50 yards. I still need to try 60 and 70gr charges, but will need to run more balls in the shop.