If you shoot buckshot in a rifled barrel you don't get much of a pattern.
The rifling causes the shot to "swirl" as it passes down the bore, and the centrifugal force causes the shot to disperse quickly as it exits the barrel.
What you get is an uneven, ragged "donut" pattern with a large hole in the middle.
Any hits on what you're aiming at are purely luck.
In addition, the rifling tears up the plastic shot cup exposing the shot, which causes the bore to lead BADLY, and the leading is very hard to get out.
Shooting buckshot in a rifled bore is safe to do, but the results are bad, and the clean up is difficult.
Rifled bore shotguns are intended for use with sabot slugs ONLY. No shot, no buckshot, and no standard Foster-type rifled slugs.