Either Heat or Proof of Life.
Heat's gunfight scene was co-ordinated by none other than Andy McNabb of "Bravo two zero" fame, formerly Brit SAS.
Proof of Life's rescue at the end is one of my favorites, although they hollywooded parts of it up (knifing sentry down with a gerber multi tool (WTF!?!?), etc.). The M249 SAW gunner point of view was really well done in my opinion.
Also, one of my favorite scenes, not movies, is in the forgettable Clear and Present Danger, when they had a gun-camera attached to Chavez's Mp5...I found this to be a very cool shot to use in a gunfight, with the recoil bouncing the picture, and giving the audience an idea of what the sight picture in a knock em down, drag em out gunfight would look like when everything is going crazy.
As for Midnight Target's answer, that put a smile on my face for a couple hours or so. I just can't stop laughing during parts of that movie.