A good gunfight can make even the most awful movie watchable.
Gunfights are the primary reason Action Movies exist. Sure, movies have escape scenes and car chases, and those are great, but they are usually filler to keep you interested between gunfights. Many great gunfights are one-sided; the protagonist empties round after round after round (and for some movies, after round) of hot lead into bastards and assholes of all shapes and sizes, and never takes a scratch.
We suspend disbelief, because those sons of bitches are badass.