I do not seem to have permission to add a photo. I will work on that. Basically, the gunk is not very thick, more like tarnish. Handling them gets my fingers a little dirty. Some rounds have some black spots, but they are not showing up on the photos. There is some talk on the internet about the brass expanding at firing and grabbing onto the rough parts of the chamber. Which is why the chambers are not perfectly smooth. I am only guessing, but I thought the tarnish may be putting gunk on the chamber wall and contributing to the jams.