I ran into a guy 10/12 years ago at a show that had a m77 tang 257 he stated was American Black walnut and was 2x the going rate for a "standard" m77. He must have had the only factory m77 stocked with American black walnut as I have never seen any other with this claim. Is there any truth to that or was he just BSing hope to cash in?
I'm not aware of standard M77s being stocked in any type of "select grade" of walnut. Ruger would buy rough walnut blanks by the thousands, and machine them by the thousands.
That being said, some of them, especially early ones, had absolutely gorgeous wood on them. Just random luck of the draw.