Many AR fans love building their own platform and one of the big thing to get if you like drilling the lower yourself, is getting an 80% lower receiver. 80% AR-15 Lower Receivers is a piece that have not yet reached a stage of manufacture to be considered a firearm. The term “80%” is an industry slang and not endorsed/used by the ATF. Did you Know? When you get your 80% lower, there isn’t any serial number on it. So once you’ve finish drilling your lower, do you need to put a serial number? No, you don’t have to but...