Luger Carbine hanger & serial number

I thought that was going to be the answer. So how do you make a carbine with a fore stock? I would like the stock not to recoil with the barrel, but cannot think of how to attache a hanger and not ruin the serial number. I guess I can attach the stock to the barrell, but then it would move back with the barrel. That is if the long and heaver barrel will move back at all. I have the barrell attached and ready to test fire.