I used a tk2000 for a single season slam. They shot good, but I wanted to screw around and try for great. I had SumToy make me a double female extension tube, so I could use standard chokes. We took several of his chokes to his range (i stopped at his place on way to hunt in FL) and found the one that made it shot great. I do have to screw it off to load.
Easiest way for load supplies, wad and shot, it's just to cut a 12 gauge shell open and use that wad and shot. NOT the powder of course. For over card just use a 12 gauge choke to cut them from foam meat trays from grocery store