Isn't any weapon that gets "destroyed" essentially jammed? The weapon's parts are not unusable, it just needs to be smacked until it works right again. I could see a jamming mechanic working by guns slowly taking damage after extended use. This would force occasional gun maintenance on the crew even if they are not taking fire. It might reduce the deadliness of trifecta and quadfecta builds, but would be most damaging ships that some how acquired two gunners.