I have a cylinder bore in the mossberg, the ball casts a bit larger than .715 and fits with room to spare. I have been looking around for a gas check that will hold the ball but cannot find one. All the gas checks I have found laying around have a flat or convex bottom to them. The flat ones may work if they cave in a bit but the convex ones probably won't work. Like you say there is a lot of experimenting that can be done. I have ordered some Winchester AA white and red wads and want to try out a few different things with them. I really should pick up some fiber and card wads to try that too.

I have the newest Lyman manual, it lists 525g slug loads with plastic wads and 35g of 4756 (Remington SPS hull data) for the 1400fps range. My ball is 537g so I use a little caution and have not gone over the 31g 1170fps load. I think I will take it up to 1250- 1300fps as a maximum. Recoil is an issue as the gun has a folding stock and is meant to be carried in the quad box for defensive purposes.

If I can find a load that will hold good accuracy to 50 yards I will shoot a bear with it to test it out.