[Rocco]

Generally speaking, a stock shotgun with rifle type or ghost ring sights' that are zeroed for your run-of-the-mill 1 oz. Foster slug @ 50 yds would print a half inch to barely an inch over POA @ 25 yds and less; a couple or so inches below @ 75 yds and about six to eight inches below @ 100 yds. It's safe to say that for all intents and purposes, from ECQ distances up to 50 yds the slugs in a shotgun so zeroed should impact dead center.

However, as you are interested in using the same bead sighted barrel with both shot and slugs I'd say that in regard to the actual grouping, it's not only HOW it groups, but WHERE and HOW HIGH with ammo brand X, Y, or Z. Remember that a bead is not adjustable for windage nor elevation. Those "adjustments" reside within your eyeball.