The gun smith did not keep your gun. It was taken from him by the creditors. The creditors went to court to seek repayments of debt. As wrong as it sounds, all items of value within the business are assets and can be used to pay off debts. Alas, the creditors, with court order can and do give legal title to assets to new buyers. At this point you are dealing with trying to get your title restored to you.
The best you can hope is the bank will work with you. Ask to see someone in charge, bring your paperwork and maybe they will return your propert to you. Do not argue with a underling. They can only say no. You must talk to someone who had the authority to say yes.
If not, you will probley have to stand behind the creditors in line to claim any "extra" money is realized.