Back a couple of decades ago I bought 3 muzzle loading guns a guy wanted to sell fairly cheap, a .31 single shot derringer, a .31 Ducksfoot, a .22 pepperbox. The all shoot pretty well, the .22 pepperbox is all metal, brass grip with steel barrel. It is not the most accurate gun but with .22 pellets it does shoot. I loaded an empty .22 shell and poured it into the barrels. I found the perfect funnel, I ripped off one of the black plastic ear things they stick in your ear to check it. I got the biggest one and it works great for loading the little gun. The shots were kind of all over the place but at least they were in front of the gun. I think a heavier pellet would work better since the ones I used were pretty light. I tried the .22 bullets from NA but they have a "waist band" that makes it almost impossible to get down the barrel. I found a picture of the pepperbox online. It is sold by Dixie Gunworks as the "PH0313B Gold Rush Pepperbox Brass frame .22 Caliber" Apparently they were sold back in the 1990's and the ones they have for sale now are basically parts without a mainspring.