Smart man. I wouldn't have touched the thing either.

My advice to whoever has it is to destroy it fast.

You are probably correct. I remember reading somewhere that the violation was due to a measurement error and was clearly unintentional, as who would deliberately cut to only 1/4 or 1/2" below legal minimum? The point to be made is that even the most minor unintentional infraction may be treated with draconian severity if you are unlucky.

Destroy it immediately as mere possession gets one 10 years in the pokey. If it is even seen by a federally licensed dealer or gunsmith they are required to report it or risk losing forfeiture of their license at a minimum. I used to work in a pawn shop. A fellow brought in a sawed off rifle that he had no idea was illegal. We had to call the police. Figured he'd turn and run but he just calmly waited for them to come and arrest him.

Local PD arrested him? Thats unusual, I would expect maybe he would forfeit the gun. Without any intent a case like that would be difficult to prosecute. BTW You won't get 10 years for possession, unless there are other crimes going on. Guidelines don't support that type of punishment.

Best way to fix shotgun barrel is to permanently attach an extension to make it legal length.

Yep

That happened over 30 years ago. And yes, local PD arrested him. And I was talking of a rifle both the barrel and stock had been sawed off. It was not legal for either barrel length or overall length, and I'm sorry nothing has changed in 30 years when it comes to ignorance and the law. He was trying to sell/pawn it as a pistol. Earl