When I saw your thread the first thing I did was to see if you lived in a high humidity area. I would imagine that the humidity is kind of low in Tucson. I live in Missouri and we are moderate to high humidity and I have not had any problems with rusting using WD40 and then Breakfree for a lot of years. I would be curious to know where the gun was stored. You have some good information as to removing the rust but I hope that you don’t have more in the future.Thank you for all of your suggestions. I do not know why it is rusting. My other pistols do not have this problem. This is alarming. I am just going to have to regularly examine and maintain them. I will purchase copper wool. There is this cloth that is made up of copper and a cloth type of material. This should be very mild on the cylinder. So I will first try this one. I will get this handled. This is happening to one of my 1849s. I have two. One has a longer barrel than the other.