Thank you Red Leg.Congrats. A nitro-proofed hammer gun by that maker is a rare find. The Jones underlever is not the quickest reload, but it is the strongest locking action ever made. Assuming the bores are in good shape, you found a very special thing. If the previous owner can't help, be patient working up a load. I bet you will find one it shoots.
Where are you located that has those sorts of restrictions?