Airsoft is quite an uneconomical way of shooting a short film. There are more easier ways of getting the required props that you need. I too am currently working on a film project involving the use of prop fire arms. Recently we have found that it is easier to rent from an actual prop company which solves your issue of legalities. Of course you will still need a filming permit. This is also a cheaper alterative than buying airsoft guns for props. The only requirements is that you have someone on scene with the prop firearms, who has his PAL and is fully aware of saftery proceedures.
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