I am thinking of building an AR pistol in 223. What I would like to know, does the lower have to be marked Pistol only, or can you use any lower for the build. I would also like to get some feedback on the best 10 or 11in. barrel uppers, or complete kits.
Seems like I heard recently that according to BATFE, you can now go back and forth between a rifle and a pistol if it is never in a illegal configuration.