I know the ATF's rules are you can't manufacture and sell firearms that don't have a serial #, but what if you've built a G19 clone using one of the P80 frame kits, and after installing an optics capable slide and a red dot, you decide that red dot optics just isn't your thing ? you decide you'd just as soon sell it and get something else ? it is illegal to sell that pistol to someone else ? I'm talking just one pistol, not doing this for multiple ones