bark inclusion in gun stock

[Jim Kibler]

I don't believe this is a mineral stain.  The post from P.W. Berkuta above describes the condition.  It's a stain resulting from a fungus from the bug that made the hole in the middle of the discoloration.  I've seen this condition first hand and it looks identical to the photo shown.

[B.Habermehl]

Just fix the hole if it really bothers you. It is definately a bug hole stain. Not bark.  Not a structure problem to be concerned about at all.  When you stain and finish the gun it will only add character. Depending on how the stain job comes out you may really need to look hard to find the stain and repaired hole.   BJH