Thanks to all, as always, for the knowledgeable input. First, he did manage to get the piece apart and back together. I did some checking myself last night and confirmed (I think) what several of you have said: i.e. the Handy Gun is still on the ATF no-no list unless it was registered. This particular gun is, in fact, not on US soil. My friend believes that his father did register it back in the 1960s, then took it back to his residence in Mexico where it remains. My friend has the serial number but he can't find the paperwork for it. He is wondering if he should contact BATFE when he gets back stateside to see if he can get a duplicate registry certificate. Because he is not actually in possession of it here in the US, he ought to be able to do that much safely, right? He is well aware that he can't go near a Mexican airport or customs official with it, because whether or not it would be considered legal in other respects, it is in theory capable of firing a military caliber, the .45 round, which the last time I heard was quite illegal in Mexico. In any case, it's going to stay right where it is for the time being.
