When any gun, metal or plastic, is sold as separate components, such as sub-receiver, stock, barrel, scope, etc., they can serve non-weapon functions, and were never outlawed, and never can be. Plastic, even electro-magnetic guns with graphene circuits, are x-ray undetectable, can easily be melted down to prevent ballistics tests, https://guns-n-roses94678.blogsvila.com/15601354/mass-produced-three-d-printed-plastic-assault-weapons-ramping-up