Welcome to the forum! I have never seen the mark on the front left of your frame. It most likely is an assembly mark. Years ago, when Mr Callahan, a retired Savage employee, had all the Savage R&D records, I offered to pay him to identify the assembly and inspectors for use in my book, but he declined. He later gave/sold the records to the Savage museum, who later delivered/sold them to the Buffalo Bill museum in Cody, Wyoming. They recently advised me that they had no records for the 219/220 single shots. As to the metal, I have been advised that the early actions were rust blued. The key word is “rust”. Later actions were color case hardened, apparently cheaper to do than rust bluing. If the early “rust” blued guns are later “hot” blued, the normal type used today, they will turn various colors of red or purple. I believe your gun has just naturally aged. We look forward to hearing more from you!
