If you reload for a shotgun you can knock this way back with a Lyman "sabot" slug inside a trap wad, I get 2in 50 yard groups and 4in 100 yard groups without even trying.That explains that then. And, yeah, pretty niche. I just looked at the pricing on sabot rounds. $6/shot. Thanks.
We have a shotgun only deer season though and foster slugs lack a lot beyond 50 yards or so depending on the gun/slug combination.