I think you should talk them into mounting a radar controlled 20mm instead. That way you don't have to "wait to see the whites of their eyes."
Wouldnt hold my breath for a 'veterans' discount - they can get a couple of 20 YO's out of Syria with more 'trigger time' with an HMG than most Cdn vets - and those kids will be happy to scrub the decks at night as well for clean sheets and a couple of meals a day.