Suffice it to say that when the county I hunt in allowed rifle hunting after many decades of not.....I dropped all my investigations into accurate slugs.
I got nice hundred yard groups with sabot slugs. But always somewhere between 5-10 rounds there would be a flyer that did not stay on the paper at all. I do believe that occasionally, 1/2 of the sabot stayed on for a microsecond longer than the other causing the slug to sail.
This happened with both a Winchester rifles barrel and a mossberg
I was going to have my son turn down a copper or brass rod on the lathe to the correct diameter and hand load these as projectiles.
Ironically the most accurate 12 gauge I ever fired was a fiends scoped browning A5 in full choke smooth bore. It fired Foster slugs into 2” groups at 100 yds. Go figure. It goes against all accuracy beliefs. A semi auto with a barrel that moves like a 1911s. A scope mounted on the reciever, and a full choke. But these big fat slugs were almost touching at 100yds.
Go figure
That is a wonderment.