Could you provide the exact place in the code where this is? I'm not sure I have found the full text of the '94 ban, but the grandfather clause in HR1022 just says "firearm" and the definition of a firearm in 18USC921 specifically states that term includes a receiver or frame. Since the lower receiver is what has the serial number on it, and is legally the firearm the rest are just parts, including the upper. I don't think the law says you can't replace any parts on a preban weapon, but if it does I would like to see where it says that.KaiserB wrote: Lowers will not do you any good... they have to be assembled into operational weapons prior to any ban. Take a look at the 1994 ban definitions. If you assemble a preban lower into a rifle after the ban, it becomes a postban (illegal) rifle.
Of course I suppose that a future law could prohibit the sale or manufacture of uppers, especially ones with "bad" features like threaded barrel, flash suppressor, heat shield, etc.