Ed Good,
If someone buys an antique double from you, and subsequently saws it shorter...please tell me by what clairvoyance you are able to judge at the time of sale? Remember too, sawed off isnt illegal everywhere, so long as its 18.5+. Also, GOOD guys use sawed off guns for defense, too.
Buy and sell as the law prescribes. If someone seems shady, then by all means CYA and make them do an FFL transfer. Of course, that judgment only works if they are standing front of you...not if they're at a distance on the receiving end.
Im not saying a dealer isnt within his right to play it safe. But let that at least be based on something a little more hair raising than "I dont know them." Im going out on a limb and assuming theres a slightly larger number of people in the world that you dont know, than you do.
- Nudge