Hi Demonwolf the last gun I put in for proof (re-proof at Birmingham Proof House) was about six years ago now and from what I can remember the gun has to be physically safe. It also had to be on face the bores had to be from what I was told clean polished and showing no flaws, also the guns lock up mechanism had to be in correct working order. The gun had to be submitted to the Proof House by a registered gun smith, now the one strange thing I found was the gunsmith I used tightened the action so much tighter than what the gun would normally be to open. He said that if the gun passed proof he would then re adjust the gun so it would open to what I would call normal. Now you must also realise that the gun smiths reputation is sort of resting on the quality of his refurbishment of the guns he submits to the Proof House and of course he wants the gun to pass proof as much as you do, but all his attention to detail costs money.
So unless the gun has a high re sale value or a family heirloom proof can be the proof of diminishing returns in the money sense.
