I believe this, or something similar, was posted ages ago but I think it's another one that should be considered for adding.
The ability to fire into the air at no target, in order to get everyone's attention and scare everybody. In so many classic scenes, the first thing the bad guys do when they crash a party is spray a handful of bullets into the air to freak everybody out.
https://www.youtube.com/watch?v=m4JwlAajmj0
(great flick if you haven't seen it)
Again, it's the crack of the gunshot we're looking to add with this one, giving people the chance to run like hell or hero up.