While sighting in my Tracker II 20g, Winchester rifled slug gave me a dead-on bulls eye at 50 yards, from the bench, no sand bags or rest.
I am making some recoil reductions mods and when I get back to the range I will finish the sighting in process using $8.75/15 rounds from Walmart.
The leading is the only issue, but it should not build up very fast.
So pay a huge amount for sabots, or a lot less for rifled slugs, that cost you some elbow grease to clean the bore every 20 shots or so.
I took weeks to research the web regarding rifled slugs in rifled barrels. They do no harm to the barrel, just the leading issue.