Howdy, I recently acquired an original Browning .22 auto pistol owners manual from the 70's. Unfamiliar.

Mostly just hoped I could get some questions answers. Still think yall would just enjoy this. I do, you don't find stuff like this everyday.

Are these legal to sell with a serial number in them? Might be a stupid question but I'm not super versed in gun law. Is there some obligation to find the gun it matches?