Yea Gods, Danny! When you say that:
The gun fixings in the wings were apt to work loose with the vibration of firing.
You mean that the guns themselves were working loose in their stowages? How on earth were these aircraft ever offered for service in such a state. Didn't Vultee have some responsibility here, or were the guns fitted outside of their control? If so by who?
The aircraft seems to have had very little RAF input, even the Mk1 Pilots Notes being Roneo'd off if I remember correctly. Having said that, I also recall that the UK Purchasing Commission did just that, ie bought them rather than obtaining them via Lease Lend, correct? Surprising then that we didn't have some recourse to the manufacturer or the US Govt, depending on who we paid for them.
I suppose though that the real world meant that you were in Burma, a long way from AHQ Delhi, let alone the UK. Everything was your problem and thus any solution was yours as well. That you chose to not arm them and thus not use them seems eminently sensible. Not too much difference I guess from putting concrete ballast in place of cannon in modern FJs!