I’m watching Pawn Stars and whenever they buy a gun they go to a range and fire it, usually pre-transaction. When they are looking at an antique gun, they always mention the possibility that it may explode upon firing.
Pretend someone walks in with an antique gun, they go to a range to test it out before they buy it, and while test firing it, the gun explodes in the expert’s hand.
If the owner knew of damage to the gun, or past failures, etc. and did not disclose it to the expert, the owner may be liable for damage to the expert.
If the expert was negligent in his examination of the gun and missed an obvious problem, he may be liable for damage to the gun.
If neither party can prove that the other’s negligence contributed somehow, then neither one is liable.
Generally, a professional would have the owner sign a contract or waiver of liability before actually doing anything to the gun. I would be very surprised if the Pawn Stars “experts” did not follow this procedure.
Imagine I was left a gun as part of an inheritance. I know absolutely nothing about guns (really). If I go to a pawn shop to sell it I cannot misrepresent the gun to them. Just this thing I got. To them it would be little different than finding the gun lying in the middle of nowhere. If they fire it they are taking their own chances. I have no information to give on the gun’s reliability.
However, if it was my gun and I knew it had a habit of misfires and neglect to tell them about it (because I want more money than I would get if I told them the gun was defective) then I would be responsible.