Brian - He owes a full return on every dime spent on the gun. He's supposed to be an expert in his field and he missed a crack that big? I seriously doubt it. But even if he did miss is, it was a defect that rendered the gun to be NOT as advertised and he is responsible for his advertising as well as for expenses incurred as a result of his error.
Those are the "rules" and he can't break them? Who says so? Who MAKES the rules? HE DOES! And he can break or alter any of his rules as long as it benefits his customer.
This guy needs to come clean or suffer the consequences of bad 'Internet' press.