Other than a mental confidence factor, I don’t believe these make any appreciable difference(except a possible negative effect). Focus needs to be on the target, not the barrel.
My uncle was given one of those magnetic sights and thought it was the cats meow. One day he was really hot on the ducks……could not miss. He was bragging on how that sight made a difference………until I pointed out that his gun did not have one…..as it turns out, it was still in his gun case. Proper mounting and form override any gimmick…….
Personally, for positive effects, I think the 20 dollars would be better spent on ammo and some clays.
My $.02 – Tim