Just picked up this .22 Derringer to add to my Iver Johnson collection. It is a single shot .22 short derringer made between the 1870's and 1880's. Everything seems to function fine, but it looks like the pins have been replaced at sometime and the trigger spring has been replaced with a coil spring. It is a bear to pull the hammer back as the mainspring seems like is stronger than it should be. I plan on replacing the trigger spring with a correct V spring and replacing the pins so they are not mushroomed. I am also curious as to what holds the barrel bearing in place and if there is a lever or something that interacts with the hammer. I know there is not a great deal known about these since Bill GoForth wrote about them a few years ago, but has anyone had recent experiences with these and what do they go for today?