Shotgun Pellets/Shot From A Slug Barrel

Two words: Don't.

Carteach0 once again delivers the goods with a test you always wished someone would do. Well he did it, and took pictures.

Summary: the rifling does indeed send shot flying all over the place. It might be good if you got up in the middle of a flock of birds, but not so much if you wanted to hit one in particular. Possibly good for crowd dispersal from a distance great enough to inflict pain and minor injury without killing the useful idiots people in the crowd.

. . . not that you would ever need to do such a thing. But, you know, if you did. . . .

(besides which, you would still have a rifled "slug barrel" for when you had to take out one person deer with a high degree of "do it hard"-ness.