Ed,
I will start out as always by saying this is entirely MY opinon and I have come to such an opinon from years of constuction and firing of cannons and mortars. I would view sand in the same way as I do cat litter and I know people who use it religously. Both of which have the ability of being packed very tightly, and in a 2 1/4" bore would take a sizable amount to seal the breach. I use damp news paper when wadded is No larger than the size of ball the cannon would fire if loaded with spherical shot, in this case a wad of newspaper 2 1/4" in diameter It is then seated against the powder NOT packed. This loading method has worked for me more times than I could count and the report is plenty loud. As far as powder goes 2oz in a 2 1/4" bore would be plenty enough by far. I am against cat litter, sand, clay, mud, matchbox cars, plastic army men, tin cans, rocks. ALL of which I have been told people shoot in their cannons.
I personally do not use pyrodex, it is my belief pyrodex is a modern made powder it may burn cleaner than black powder but it also burns faster. I have talked to Reps at Hodgdon and they suggested cutting the loads in half if using pyrodex in lew of Black powder.
We use Goex and only Goex and in 15yrs of firing loads as large as 1lb in a 3" cannon have had no problems!
Hunter (dixie) can Replace your cannon ...They cannot replace your life! before loading any kind of projectile be it paper golfballs or zinc shot instpect your barrel closely and think it out is there anyway this will bind up or get caught in the barrel, How much pressure might it take to push this out (in a Millisecond), will it be easier to blow this out of the barrel or for the barrel to burst.
As I said this is just my opinion..
