Victor3,
The shot from the Parrot was using one of the bullets from your mold. They work great, however 300 grains of powder is really sort of weak in the "boom" department, 400 is much better. More than that causes TREMENDOUS recoil, much more volume, and hence structural damage to the oak carriage (don't ask me how I know...). The Parrot is back in the shop waiting on new "cheeks" to be cut out and painted...
I'll tell you the truth, it seems that shooting mortars is much more fun than shooting cannons. Easier to load, reload, clean, and you can see the projectile (usually). I think the best projectile for the softball mortar is a concrete filled disposable propane cylinder. These seem to fit just about right and are heavy enough to carry a good distance. The softballs are a little bit too loose, but work and are require no "prep work".
BTW, I didn't know BornSouthern34 had "the bug", I can HARDLY EVER get him out to shoot...
NitroSteel