Very nice stock!
I wonder why walnut has been, traditionally, the sigle wood choice for gun stocks.
By far the best common wood, worldwide due to mechanical characteristics. Only one NA wood has better mechanical properties when comparing equally dense woods. That would be bigleaf maple, but it is usually much less dense than walnut. Among the characteristics making a difference (in no particular order) would be stability in use, bending strength, hardness, average density, beauty, tendency to (not) split, shrinkage rates in the two major cross-grain directions, ease of drying, and others. Many are great in a specification or two, few are close in all the categories.
Maples are okay, but usually if they are tough enough to be really good they are mighty heavy. And because the various strength characteristics vary due to many mechanical properties just being heavy is not everything.
Myrtle makes a beautiful stock and performs well, but it is quite difficult to dry and supply and distribution are lacking.
Weatherby used screwbean mesquite for a while on some stocks, but it is rarely big enough.
