A bead is fine as long as you don't lift your head as others have informed you.

We point a shotgun but aim a rifle.
However, with today's tight shotgun patterns due to our turkey chokes we use, we lean more to aim the shotgun as you are aiming at a small target. Specifically the head/neck above the feather line of the neck.
Pop one in the body and surely the chase will be on. Very sickening feeling knowing you hit the bird good -even rolled him down the hill, but can not find it.

Been there done that.

As soon as you lift your head - even a slight lift you have lost your aimpoint.

Just my 2 cents.

Didn't cost much to allen wrench on some true glo sites I could adjust for windage and elevation. Never lost a bird again.

JW