I'm really not surprised that that the shot went unheard. The only time we've had a noise complaint in this complex is when some old people lived above us, right after we got Guitar Hero 2 (and surround sound). Thats one aspect of this complex thats done right.
Had this happened with both of us home, at around 10:00pm we might very well have asked him in for a beer, talked shit about guns for a while, and turned it into a learning experience. 3:45am is no time for such things though.