David, if you determine that a 1900 OO grade would have used the same steel as this gun, and would like to test a small piece to determine content, let me know. I had everyday access to a Met Lab until about 2 months ago, but I won't have easy access again until late spring or summer. A couple of the guys I knew who worked in that Lab were gun guys who would have happily done spark, Infrared Spectroscopy, hardness testing and whatever else they do for free, or a beer at most. Government work, you know.
Maybe someone else here has similar access now at similar cost.

A true sign of mental illness is any gun owner who would vote for an Anti-Gunner like Joe Biden.