I recall reading language along the lines of "components that seal the breach", in which case yea, sounds like uppers would be f***ed.

{ āReceiverā, the part of a rifle or shotgun that provides housing or a structure for the primary component designed to block or seal the breech prior to initiation of the firing sequence, even if pins or other attachments are required to connect such component to the housing or structure. Any such part that is identified with an importer or manufacturer serial number shall be presumed, absent an official determination by the Bureau of Alcohol, Tobacco, Firearms and Explosives in the United States Department of Justice or other reliable evidence to the contrary, to be the receiver of the firearm.}
Eta Frame language
{āFrameā, the part of a pistol or revolver that provides housing or a structure for the component designed to hold back the hammer, striker, bolt or similar primary energized component prior to initiation of the firing sequence, even if pins or other attachments are required to connect such component to the housing or structure. Any such part that is identified with an importer or manufacturer serial number shall be presumed, absent an official determination by the Bureau of Alcohol, Tobacco, Firearms and Explosives in the United States Department of Justice or other reliable evidence to the contrary, to be the frame of the firearm.}
Last edited: