is that still a thing? or it is completely banned?
Depends on the manufacturer. You cannot SBR something that is banned by name. For instance, you can't SBR a C39v2, because the rifle version is banned by name. The rules don't make any sense. I know people who have been approved and some who have been denied. I called up the ATF and was suggested that what I just told you is generally how they decide.
I ended up selling my C39v2.
God this makes no goddamn sense. How is a short barrel rifle not a rifle? What absolute coke fiend writes this stuff?