You guys talking about milling - you'd have to set up the whole receiver in the jaws of he vise - at least I think you would. The locks on a hammer gun are usually held in the stock with a screw that goes from the left lock to the right lock and head of the screw is located under the left hammer - the one buggered up. Maybe you could just clamp up the end of the receiver - just some thoughts. I'd just carefully grind a bit off hopping not too much grinding is needed.