Thanks Cat. That sounds about like what Cannonmn was suggesting. A hollow based wadcutter. And thanks for giving some dimentions, I wasn't sure how thick to make the walls of the skirt.
This is sounding more and more doable for me. I don't have access to a machine shop, so I have to work on the cheap. Maybe some pipe or tubeing with the proper ID, get a cylinder hone and polish the inside, and a mandrel with some sort of jig to keep it centered. Maybe have a machinist put a slight taper on that so it is easier to remove.
3" schedule 80 steel pipe has an ID of 2.9 inches. My bore, land to land, is 2.97 near as I can make out (odd number of gooves makes it a little harder to mic it), and groove to groove is about 3.1 inches. Should work.
Dimensions. Overall length of about 6 inches (two calibers) sound about right? With a solid nose about two inches, and then 4 inches of skirt. That should weigh about 8 to 10 pounds. I can experiment and get the weight adjusted to what works best by changing the length of the skirt a bit.
At the only live fire we have been to we had tried soda cans partially filled with concrete (I told the guy cement, but he went cheaper and got a bag of concrete mix), cut the tops off so that we had a flange of the can to try to catch the rifling. We used a 6 oz. charge of Fg. From what we found, it looked like the Al melted away, although some of them showed evidence that the front part had expanded and caught the rifling. We had also tried making a sabot of foil. That met with mixed results. But, overall I was happy. First time trying it, my lateral spread at 200 yards was about 5 feet judging from the marks on the ground. And obviously my elevation needed some help. I did manage to get a few onto the target, though. And we all had fun.
Cat, what the heck is the "Pulaski Coehorn Works & Winery"? I can hear it now "Interesting nose, bright, sparky, a hint of sulfur and a wiff of grape" "The flavor explodes on the tongue, then lingers on the pallet with subltle undertones of burned powder and gun greas"