....
I wonder if the lab did find graphite inclusions in the barrel, that it made for a higher carbon content, but the carbon available to form steel might be closer to that 1018 that you looked at. Possibly not a true medium to high carbon steel component of the damascus.
I am fairly confident that the "steel" component of old damascus barrels was actually high carbon steel. At that period in time, they fully understood what high carbon steel was and were capable of producing it efficiently. I also base my analysis of the material on its reaction to etching with ferric chloride. It etches and colors very similar to the 1084 steel that I use for knife blades. The reaction of steels to etchant solutions, can tell a lot about the alloys in the steel and also help to display the grain structure....
Thanks for your time Steve. I hope follow up thoughts are okay, not questioning your research and experiences. I'd suspect if wrought iron were used as one of the components, that the overall carbon percentage would even out to at best to what might be considered medium. Also, I think etch appearance of modern steels might be affected by added manganese, that would be interesting to know what amount may be present in historic barrels.
I've also noticed that barrel bulges are a common type of historic and modern barrel failure. There are many historic accounts of bulge repairs by hammering down and refinishing bulges. Even today it's a viable repair possibility and tools for slowly raising dents are available. My take on the mechanism of plastic barrel failure and the possibility to cold form it back may(?) be more generally successful on low carbon steels.
Thanks again for all your time, and thoughtful explanation, Craig
