I did not mean that a gunsmith can restore it to its unused condition, Jaddak. Thats ridiculous. If the buyer has wrecked the value with use- which I understand he did- then the seller's offer to help with getting a gunsmith to return it to functional is more than fair.
Geez, dude!
When I buy a gun, I think it is reasonable to expect the gun to function properly. If you disclose to a buyer that the gun doesn't function properly, I think the as-is argument would apply. If you didn't disclose it, then there is reasonable expectation that it will function properly.
Your...
I would inspect the gun myself. If the gun is still in the condition it was at the time of sale, I would refund all his money. You didn't mean to sell him a faulty gun...but you did. Take the opportunity to be honorable.
**edit**
I now understand that it is impossible for the gun to be...