Dont listen to these ppl..Finish it.. put some jb on the bottom.. itll be fine .. the only thing you really even need a bottom for is the trigger spring pressure, and i think jb would hold fine..
As long as its just for plinking at the range whats it really matter to try?
Eta.. that looks...
I did not see anything in the bill that said anything about caliber... so without a specific exemption for caliber.. ide say not to.. only exemptions for an ar15 rifle is hbar
I use a credit card/ID for the pivot pin (Its super easy) ... and taped pliers for the roll pins.. they both work great.. I have no tricks for the castle nut.. I always use a castle nut wrench
.. you know what you're gonna do with the upper yet?