It was all done legal I can assure you. His uncle owed him money and decided to give him the gun as payment.
I wasn't accusing your friend of
intentionally doing anything illegal.
In some states (like my state, NC) there are very strict laws controlling how guns can be bought or sold, and the law specifies who can do it and what must happen when doing such a transfer.
If you're unfamiliar with the requirements or procedures for your state, you may want to check out the appropriate transfer laws, just for your own peace of mind. A transfer between state residents is controlled by different laws than transfer between parties when one lives in a different state, for example.
Knowing the details of your state's laws will help you if you later want to sell the gun and maybe keep you out of trouble farther down the road. If neither of you have "jumped through the hoops," it's not too late to do so, and you can get the paperwork straightened. It might be quire simple.
(Here in NC, for example, unless you do the transfer through a Federal Firearms Licensee/dealer, you can only transfer a handgun in a private sale to a state resident who has a pistol purchase permit or a concealed handgun permit.
Anything else could get you in trouble and cause you to be fined or lose your right to own or buy firearms. It could get really ugly if you sell it to someone not allowed by law to have a firearm, like a person with a felony conviction in their history. It can get sticky.
Your state's law may be even more strict than NC, or less so. You may want to find out. Transferring a handgun privately to a person who isn't a state resident is a BIG NO NO, as that type of sale/transfer is controlled by federal law. If his uncle lived in another state, for example, that could be a little bump in the road that has to be addressed.)
