I don’t know about mobsters but do remember when Israeli agents murdered the wrong person in Norway. They meant to kill a terrorist but got the wrong person.
I do remember clearly that the weapon was a model 70 Beretta in .22LR.
Of course your typical gang banger is not going to let you sneak up behind him. Still the .22 is better than most think.
I didn't intend to imply that the .22 LR was not a useful assassin's weapon. It is. Ruger made an integrally suppressed Mark II for the US Navy.
It's the bullet bouncing around inside one's skull that is silly.