I am curious as to what and when the damage is done to a double barrel that has been blued incorrectly (hot blue). I have heard the solder is or could be damaged by the process resulting in loose ribs. If a double has been nitre blued and survived the process with ringing barrels and no visible damage will it remain "OK" in the foreseeable future? Is there a possibility of any residual salts continuing to eat the steel and thus cause a loose rib later on? If the gun remains solid after a nitre blue would a proper slow rust browning mitigate the potential for a loose rib problems later?
