Oh my goodness, this is surely going to pull me into the black hole of time..... lol.
Years ago I fooled around with trying to duplicate Remington factory sabots - those were a .22 caliber bullet loaded into a 30-06 cartridge.While in theory these shoucdl have worked great, they just weren't accurate. I would love to know how these 38 spl cased sabots work out for you. I've got a couple of .357 mag revolvers but I'm thinking that this type round would surely be fun in my Blackhawk, especially because of its 6" barrel.
I'm curious what drove you to choose this arrangement - was it because of the available components or were you specifically working on something for a revolver? You've got me thinking about what could be done using a 45/70 parent casing.
Blessings
Paul