[Armorer-at-Law]

The FFL doing the transfer is legally required to know who the firearm came from and to record his/her name and complete address in his acquisition/disposition book (bound book). The surest way to do that is to require the sender/seller to send a copy of his ID, such as a DL. It really is not unreasonable to ask. If it is sent with nothing more than a Gunbroker user name and partial address, it really puts the FFL in a legal bind. This is why some FFLs will only receive guns from other FFLs (no private party transfers). Some even falsely claim that it is the law, thinking that will satisfy the customer better than the truth.