Yes you can do that, but your accuracy will be in question. The sabot must have a fast twist from rifling to work or shoot straight. The patched round ball will need to be a bit under sized to fit through the choke with out being deformed too much. An improved cylinder or cylinder choke, being the best would help. See if a cylinder choke is availabe, if not, a regular choke can be reamed out to open it up. Another option is the Lyman Cast slug that looks like a large Crossman pellet. They load in a regular plastic shot wad and are very accurate out of my regular shotguns. Don't see why they would not do well in an inline. The choke needs to be removed to load, then replaced for the shot.