Those guns were fired.  A few frames from _Return of the Jedi_:

![falcon firing 1][1]

![falcon firing 2][2]

![falcon firing 3][3]


  [1]: https://i.sstatic.net/3kV9m.png
  [2]: https://i.sstatic.net/M9dCj.png
  [3]: https://i.sstatic.net/OVPsz.png