Looking For Info About Luger Parts (Pic Heavy)

[alanint]

The only place the "Rifle-Pistol" receiver disctinction is made is with the AR family or weapons. (ATF tried to do it with the Thompson Center family of weapons, but the court shot them down). If an AR lower receiver is sold as a pistol, it cannot be later made into a rifle.
Stupid, yes, but its the goverment.