Tony, Black powder comes in several granulations as you probably know. The ffffg being the finest , fastest burning and is intended for pistols. Muskets used ffg as a rule and generate a slower combustion so that should work just fine. I still would fire the thing with a heavier ball and charge accompanied by a looooong fuse the first time. I would light the fuse and go around behind the barn to admire the rutabaga blossoms until it fired the first time. It sounds like it will hold, but with cast iron, one is never sure. My 1860 Ordnance manual (US) says that the large cast iron Columbiad seacoast cannons would burst, but no one could predict when it would happen. Sometimes they burst on the third shot, but the author knew of one that had fired over 1,300 times and was still in one piece. I would imagine that artillerymen kept a tight you know what every time they fired one of the things, because it WAS going to burst sooner or later. He went on to show via some drawings exactly why it would burst and showed a design that was supposed to be as perfect as possible against bursting. The barrel had to be perfectly rounded with no ornamental rings cast on it nor should it have a cascable or its trunnions cast as part of the barrel. Trunnions were to be made of bronze and fitted to the barrel with a sort of bridle like affair. Guns made to this pattern proved to be pretty near burst proof, even more so than the Brooke style with shrunk on wrought iron bands like the "Long Cecil" breech loader of Boer War fame. Jesse, the former CSA Artilleryman and waver of Confederate flags when possible. I have a Southbend Colonial field cannon at 1:10 scale, in cast iron with a stainless steel liner, and it weighs a lot less than 17lbs! It still have a .600" bore though, so that I find 20-guage shotgun solid ball and wads "would be" ideal ..... but I didn't say that! <VBG> 70 grains of black powder goes well in a .577" Enfield musket, and so should be about right for this cannon of mine. Weight for weight, for similar recoil, a charge of 120 - 140 grains would be about right for a 17lb barrel, so about an inch bore perhaps? I would stay away from shotgun cartridges though, as they have different impulse / pressure curves due to their nitrocelluse based smokeless powders, unless you use a steel liner, which then becomes the barrel and chamber with the brass tubing just there for show .... Tony. MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.