TC, shooting from an a/c would actually require re-thinking from ICAO and the UK Government rather than CAA as it is contrary to the Chicago Convention to fire weapons from a civil a/c and as the UK is a signatory to that it would be illegal under that International Treaty. Don't ask how the Bundespolizei do it....if they do of course, not to mention the land of the free {except for those in detention camps of course :>) }
Before you ask TC.....soon.