Uhm....

[KingFuse]

its callied fukin uc

[Arkasia]

Quoting all the previous responses, I would say there'snt such as a certain cience about aiming to feet/chest/head since all the bullets spread in one shotgun shoot arent the same.
What I do depends on the distance between my enemy and I, if they are far away, I try aiming to their chest in order to hit as many bullets as I can in one shoot, and if they are close range, just try aiming at their belt.
Hope this was useful for you, good luck

this is coming from a god, please listen

[Joobie]

this is coming from a god, please listen