Rat,
I'm using Remington Copper Solid sabots with great results, but they're for rifled barrels only. I have recently tested some Brenneke KO slugs, around $2.30 a box, and had almost as good of accuracy, and they work well in rifled or smoothbores. The Remingtons are around $13.00 for 5. After the season is over, I'll re-sight in for the KOs, much cheaper than the Remingtons, and similar results.
MH