Dogwreck, I'm sure someone with more knowledge will chime in here shortly. You've got a lot going on in your post. I'm more then a little nervous with some of it. "Pipe" always makes me cringe, DOM tubing, maybe and not by itself, never pipe. You say you want to shoot salutes (blanks) but what about your grandkids, almost all cannons out live their owners and we have to worry about who uses it next and how. We wouldn't want some unknowing soul to fill it with powder, load a ball, and make a bomb. You also say you're new to powder and cannons, we all were at one time. Powder for cannons is BLACK POWDER not smokeless powder which is in those bird shot rounds you made into blanks. Smokeless powder is way way more energetic than black powder and a sure fire recipe for disaster. I am not trying to scare you off in any way cannons are a blast (still learning myself) just hang in here and let the pros lead you in the right direction. Neil
“I won't be wronged. I won't be insulted. I won't be laid a-hand on. I don't do these things to other people, and I require the same from them.”
― John Wayne "The Shootist"