In this video, Taofledermaus shoots a stabilized discarding sabot shotgun round to find out how well it actually works.
A standard shotgun slug has a gas piston to push it through the barrel. This is a different kind of slug designed more like a military sabot. The idea behind this design is to increase precision by distributing the force evenly down the length of the slug. As the gas expands, this creates the effect of the slug being pulled evenly along the barrel rather than being pushed from behind.