I was shooting some pics for a few new shells I posted over on the sales side and so shot two images of Read sabots showing something different. This picture is of two with the most typical round hole and no other design point to to assist with preventing slippage other than friction of the brass/copper on the iron. The one that still has the iron center piece is from a 3" shell fired from an ordnance rifle and has a steep slope to it. The more green one below is from a 3.25" Read shell found at Blakeley, AL. It has a large center hole which held the typical so called "Selma Blob" which was a nice rounded pancake looking base knob. It doesn't have nearly the slop as the top one.