Airsoft and the Policing & Crime Act 2017
How does the Act affect airsoft?
From the 2nd May 2017 the Act introduces an exception from the classification for airsoft guns as firearms, so long as they meet certain criteria.
This means that airsoft guns (and it doesn’t matter how they are powered) are not firearms if they are designed to fire a spherical plastic missile that is no bigger than 8mm in diameter and they have a muzzle energy that is no greater than 1.3 joules if they can fire successive shots (often called “full auto”) or 2.5 joules if they can only fire individual shots (meaning either “single shot” or “semi- auto”).
More Information can be found Under "What Is Airsoft" link