Rifled shotgun barrels are for shooting sabot slugs ONLY.
Attempting to shoot bird or buckshot has big problems.
First, the barrel leads up like you wouldn't believe, and it's HARD to get it out.
Second, the rifling "swirls" the shot as it exits the barrel, and this causes donut-shaped patterns.
The shot pattern forms a big circle with a large hole in the middle.
Hits on target are purely a matter of blind luck due to the blown pattern.
I wouldn't even attempt to fire a standard slug through a rifled barrel.
Although the slug would almost certainly fire safely, the rifled bore would "strip" the rifled fins on the slug, and leading would be absolutely horrendous.