I once heard of a group going to an airsoft event in N. Ireland (late nineties or early noughties I think). There was trouble in some estate they were passing and the army had thrown up a checkpoint. When asked is there anything in the car we should know about there was an 'ummm, in the boot but none of it's real,' squeaked out of one of the nervous passengers and the squaddie had a look. Then they were swarmed with all the soldiers coming over to look enviously at their kit as they had more guns, grenades and body armour. After admiring their arsenal and checked it was all airsoft stuff, they were let on their way.
BTW some of the airsoft rifles are powerful enough that if you modded them to be automatic they would require a firearms license but that’s a different kettle of fish.
Anon as I don’t want to waste months of my life on a nonsense charge.