Use a pump gun as a basis (so you have more options regarding magazine capacity and barrel lenght), make sure the barrel you use, whatever it's lenght, ihas NOT been shortened in any way, shape or form. Make sure that the gun cannot be folded down or otherwise shortened (without tools) to an overall lenght of less than 660mm. As long as you do all that, you could bolt the kitchen sink to your gun if you feel like it, nobody would care.


















































