Thank you for the clarification. It had me confused when we were there. It all worked out anyway. I just sold him an old one of mine.A lower receiver HAS to be marked on the 4473 as an "other" on line 18, and described as a "receiver" or "frame" on line 29. The old forms, up until a few years ago, were different.
Correct on the law, incorrect reasoning. The law allows for sales of long guns to those over 18 but under 21. As noted above, the receiver (even with a stock attached) would have to be transferred out as an "other," which is different from a long gun. Thus, an 18 year-old could not buy a lower receiver from a dealer. Same goes for pistol-gripped shotguns (Mossberg Cruiser, et al), which are also transferred out as "other".