Originally Posted by DFlynt
Model (if known)
Serial Number (if available)
Seller and buyers names & addresses.
How much you sold it for (optional)
You could also get his finger prints, a blood sample, and a photo of him holding the shotgun, be sure the eyes are in focus for retina scans!
Seriously. When I sell an unregulated firearm face to face in this state, I google the person and give a quick look in Maryland case search just to be sure. I check the guy's ID to make sure it is Maryland and the name I got matches, then I get the cash. I don't have them sign anything, I just keep a note in my own records that I sold firearm XZY, serial number 123, on date, to the name given.
If you have any reason to suspect that this friend is prohibited or intends to do something illegal, don't do it.