Not sure on this but at the least, I'd get an agreement written up on it (date of sale, model/serial number, signature of new owner, etc.). There's a few on here that can answer this better than me....just cover your own caboose for sure.
"The government did not write the constitution to give rights to the people. The people wrote the constitution to limit the government's power."
LIFETIME NRA MEMBER SINCE 1977