A bit off subject, but I had noticed buried towards the end of Puraye's "Making Damascus Barrels" booklet ('76 American Riflemen two part article). There's comment about a section of barrel that was evaluated in FN's lab under the 'metallographic microscope'.
The time frame of the original publication puts that study in the fifty plus years ago ballpark. It was noted the barrel was 'autogenous', as your images showed, and not a bunch of seems and defects. Sorry if you had noticed that before, but maybe these barrels can be evaluated as low carbon low alloy tubes without some factor adjustment for damascus.
