I just finished a pilots memoirs and it was amazing how many times his guns jammed on him in a fight. I don't know if he was particularly unlucky or if his rigger hated him. But they put a 2.5lb hammer in the cockpits for a reason, so it must not have been rare.
It then is a tricky thing to hold off the enemy while you bang on the guns to unjam them or try and disengage and escape when you get a chance. That bit of frustrating desperation would add a little flavor.
Extra point for a hammer hitting the guns animation.
Occasional random jams (I think maybe English guns were slightly worse). Each tap of the "U" key would give you a 20% chance of clearing the jam.