I watched both this week, and have happily added them to the small list of movies that understand how gunshots are supposed to look/feel/sound.
If you don't understand the obsession, watch the bank heist from Heat with the sound turned up (subwoofer or headphones are necessary, youtube here if you insist on low quality).
Mann was one of the first directors to understand that a gunshot is much more than a simple sound effect. In reality, the sound of a gun firing manifests itself both physically and mentally, by pushing sound waves into your chest and placing fear in your mind.
In the heist scene, when the shots start firing that's the only thing you'll be able to hear, and that's how it should be. Notice, too, how each gun has a very unique sound, something many directors don't bother paying attention to. At the very least, the way a gun sounds in a particular movie reflects whether the director intends to pursue realism or simply cater to what the average movie-goer is accustomed to. Mann may not be the most balanced film-maker in the world, but he was the first to focus on realism in his action scenes and it shows in all of his movies. (Another stand-out: The use of military tactics vs. untrained criminals in 2006's Miami Vice)
Another title for this post: Why I Liked Public Enemies Even Though Nobody Else Did