No experience with the 12Ga Rifled Slug Barrel but my 20 Ga shot under 2.5 inches all day long at 100 yds. most of the time it shot smaller groups than that, never shot it any farther than 100yds. Recoil with the 3 inch 20 Sabot slugs were not bad at all but the same brand was more accurate in the 2 3/4 inch version. I think the 20 Ga may shoot flatter than the 12 Ga. Mine shot the sabot rounds with the Barnes copper bullets in it the best, sorry can't remember the brand.
Steve E....................