As stated above it is a bark inclusion, and will not materially affect the strength of your stock. I would wait until everything has been inletted and fill it with some appropriately stained epoxy sand it smooth and finish over it. It looks like it will be just to the side of your triggerguard inlet. (now why couldn't it have been under the T.G,.) Oh, BTW usually the test holes for a R.R.channel are drilled from the barrel inlet down, not from the bottom of the stock up. It is no big thing as the T.G. will cover it. Ron