If they look like a real 1:1 scale gun, yea I guess you would need a defence for them. it's not the 6mm plastic BB that the laws was intended to stop. but I understood the guy wanted to buy a RIF airsoft to turn into a paintball marker, which would surely need some kind of defence either way.
yer but hes building it for the purpose for skirmishing it as a paintball gun and skirmishing is a defence therefore hes covered, people got butt hurt straight away over it.