Well, technically ATF says you can only go pistol to rifle and back to pistol on the Thompson Center KITS that were sold with all of the rifle/pistol parts. Here is a letter from ATF in response to a request to turn an Uzi Pistol into a Carbine and then back to a Pistol. ATF said no.
Thats the Uzi and why, no telling... It can be done with pistols like the 1911. Hell if you could find a a 16 inch barrel you can do it with a glock. You can do it to a AR 15 pistol also, I cant say as to why not on the uzi, thats the ATF waffeling. They are good at that..... Why they said you couldnt is beyond me. Me.
They are making it up as they go... Dont listen to me. I read and reread the letter. They make no sence.. It was always as long as you broke the weapon down and put it in the correct configuration it was ok ( on a pistol reciever) . I guess mabey not. Mabey the question needs to be reworded differently. Mabey the Agent wasnt understanding the question. Heck if this is true Im bumbed. This is the first Ive heard of this..