Hey where are you located? Im a filmmaker too, and asked the same question somewhere
on this thread.
Anyways the response was great via PM. I suggest PMing Sgt. Haggis, I know hes been in a few independent works and he pointed me to a local armourer named Dave Brown (google it!)
Anyways, Ive looked into importing guns for movies, and at this point its just not feasable to do it, there are a few armourers out and about that you can deal with to rent you some props much better than clearsoft. Or, alternately, depending on how legitimate your filmmaking is, you can apply for a Theatrical Firearms Business Licence.... but thats a long shot and dont expect it if your anything short of an established film producer already.
Anyways good luck with the film. PM me if you need more information on anything moviewise.
Note also: some airsofters will love to be in your film if you feed them a day, the perfect extra: their own equipment, own costumes and no training neccessary