The seller of the Ideal, is proposing that the dispersal barrel would also work well with ball or slugs.

I can assure you, this would not be the case. It is for birdshot, only. The flats are clearly marked choke and raye, but, I cant make out much more than that. I would expect that the mark non pour la balle appears somewhere on both tubes,

I dont typically deal with auction houses.

Good luck.

Best,
Ted