Lots of issues here!
For a start ... if we are talking UK alone there would be hysterics in the CAA and the aircraft would probably have to go to Public Aircraft status [ie off the G- register] and then it depends what you think is actually happening elsewhere.
The USCG operations are 'just' offering a sharpshooter with the ability to knock out one or two outboard engines... although the politicians are talking about getting 'machine guns' up there to spray everyting liberally in fact there is very little of it about outside of the MGM studios. One of two US forces practice spraying gunfire out of the side doors ... but it is not really an efficient way of going on.
Most US officers carry sidearms and other weaponds for potential use once on the ground. Hand guns, cyclic and collective tend to mean you run out of hands somewhere in the plan....
Others may disagree.