I have had good result using Proydex in Pop can cal. Mortars. A pop can filled with water, frozen to ice and 360 grs, ffg will go 270 yds. Goex ffg 310 yds. Filled with a brick mortar or concrete will go futher. Tennis balls filled with sand, Pryodex will not work, it will not work with my golf ball mortars. Prydex needs the resestance to work .
Pryodex will work in a 1" bore with a light cotton patch. I have clocked them at 2250 fps.
What ever cannon you use be sure it is off a good steel, capable of the pressures. If cast barrel, then properly lined with a seamless steel liner.