Actually the "Smoke of Fun" in this case...
I ordered this one from Dom with a can-size bore and a golf ball bbl sleeve...
I finally had a chance to take it out today. I used 3/4 full cans of plaster of paris and a small wad of foil over 150 grains FFG. At ~45 degrees, it would send a can out to about 200 yds.
With the same charge at ~20 degrees, it went about 150 yds. You can see the can just above the ridge line here...
One thing I wanted to find out is if the golf ball liner would stay put without some kind of retainer. As can be seen here, it didn't - it shot out about 5 feet. Charge was 75 grains FFG. Ball shot out of sight...
I suspect that maybe the ball was deformed upon firing and grabbed onto the bore sleeve and took it with it. Or, there may have been enough pressure present at firing to get under the base of the sleeve to eject it. Either way, some sort of retaining screw will be added so the mortar can do double duty (Cans and golf balls).
Another thing that was once again confirmed in my ongoing BP mortar research is that there is no way to prevent guys who have never seen one before to refrain from giddy giggling and shouting expletives.