Because, if it can, I was thinking this could be the return of the And Stay Back! perk, if the knockdown chance is given to each shotgun pellet. Has anyone tested the knockdown potential of a scoped shotgun with Sniper?

I don't think so. Shotguns are not considered rifles.

According to the wiki, it lists shotguns as separate from rifles and that even the rifleman perk doesn't include shotguns (which is kinda harsh as would mean no perk is associated with them.. boomstick fans leftout ). Saying that I have heard the opposite from players and does indeed effect shotguns. Much confusion. I'd say best way to see is test it yourself. Let us know what find out.

PS i mention the Rifleman perk because from its wording anything that that effects should also include anything that can use the sniper perk as long as it is scoped and because it is available at lvl1 it can be tested rather easily.

But... Shotguns are affected by the rifleman perk. Taking it increases the damage on them.

Great idea...stick a scope on a close range weapon,

Yet they are affected by the rifleman perk, which would suggest they do.

Simple, just grab a scoped shotgun and shoot some raiders (while aiming down sight) and see if there're any knockback?

Then according to the wording on both perks it should indeed work.

It's a shame the shotguns didn't get their own perk, it would have been better & more fun perking it up.

There are short range scopes fyi.