I have been involved in the production of millions of board feet of softwood lumber. In softwood lumber, it is my experience that a 2x4 with the pith (heart center) usually is less stable than lumber cut from the outer part of the log. Knowledgable lumber buyers stay away from lumber manufactured from small logs because a high percentage of the lumber will end up warped. Bending strength is also typically lower in lumber that includes the pith. I don't know if the pith would cause a decrease in the compression strength which is probably the most important issue in a gunstock.
I agree with the Franchi's opinion to pass on making a stock out of this piece of walnut. I have made quite a few stocks. I learned the hard way to pay attention to the grain flow in a stock when a rifle stock I made broke through the wrist because of cross grain. It is best to start with a good quality blank that has no apparent defects from the outside.
Forester
