I shoot cheap slugs out of my USH lami heavy barrel on a regular basis at the range. 15-20 shots at a sitting. The barrel gets quite leaded. I buy lead remover cloths (about $5 at many gun stores), cut pieces off, wrap them around a bore brush and floss my Ultragon rifling with a few pieces until it is nearly clean. I move the pieces around, reverse them, etc, to get the most out of them. Toxic smell and takes off blueing. Don't lick your fingers.
Remington Sluggers shoot patterns. Winchesters from Walmart (the same $10/15) shoot 3 shot groups that touch at 50 yards.
The gun is set up for the bench since it misfires. 20x scope, cheap rings, and a bipod.
I don't remember what sabots shoot like anymore. The cheap stuff is fine for me.