KYJ
A gun which is out of proof is illegal to sell and is therefore worthless until re-proof is passed.
Any old gun is in proof according to the Rules of Proof under which it was made and tested until it is altered or worn beyond the limits of proof.
For sleeved guns or new barrels, the Rules of Proof applied will be the 1989 Rules, with CIP dimensions applied to chamber measurements.
They have told be they will NOT apply the 1989 rules retrospectively. I am currently investigating the details of this policy and how it works. I have a meeting with the Proof Master in Birmingham due next week to discuss it.
