Tks for the info. Fora 12 bore bolt gun, they looked pretty good. A recent mangazine - maybe Rifle, has an article on them with sabot loads tested for accuracy at 100yards.

My Mossberg m835 has a .724" groove diameter - sung.
I've a few rounds loaded with the .58 sabot and double round ball loads, but so far, haven't papered it. I thought they might make good Spring Black Bear loads. Good to note about the sabot diameters - thanks again.