I removed the brass plug and the burst disk is under it. I have since found the leak to be the fill port. I have to remove the fill port and replace a seal. I don't know if my heat gun is hot enough to get it to break loose.
I removed the barrel and stuck the fill port in a bowl of water. I saw bubbles coming from the fill port.
First, stop using ammonia for a anything cleaning agent. It is a strong chemical. It can damage wood, it's finish, bluing, seals. Rust the barrel. (Even see the damage urine does to metal fixtures? Take a look next time your in a public restroom. Very caustic stuff!Oh, and DON'T pee on your gun!!! Pick a tree that your gun is NOT leaning on in the woods. Put a party balloon over the muzzle to check if it is a valve thru the barrel leak. Cock the gun and see if it still leaks down overnight. (cocked, it will not leak thru the barrel, as it will no longer be sealed). Knife