Planning on building one. What are the specific rules I need to follow? Does the lower just need to be “registered” as a pistol? If it is can I change it to a rifle at a later date if I wish? What about an OAL? Min/max? Is rather stay on the right side of the law and not have the atf at my door
If you do some searching I think you’ll find plenty on the subject.
If you buy a stripped lower, it’s an “other”. Then you build yourself a pistol if you want.
Someone with the details will chime in, or will direct you to the search button I’m sure.
If you are building one, use a lower that has never been part of a rifle or at least has never been part of a rifle on official paperwork. You can build any length pistol you want. I would stay above 10" unless you are going 300 blk. Dont put a vertical grip on it unless your pistol measures over 26" from the muzzle to the end of the rear extension. You can always go from pistol to rifle but you can never go from rifle to pistol.