Tom: I wouldn't hesitate to use that wood. Once you have the gun roughed out, mix up some AcraGlas from Brownell's, stain it very dark brown, set the wood under an incandescent light bulb for 15 minutes, or heat the wood gently with a gentle heat gun, apply the runny exopy letting it absorb as much as will go in. Once it puddles, apply a piece of clear packing tape over the puddle. That will keep glass at the surface and eliminate air bubbles. When it cures, remove the tape, dress the wood down to final, and finish. If the knot offends, stain the whole stock dark and call it a beauty mark. Or leave it loud. As I have said in the past, good stock wood doesn't grow on trees! The stock will be lots strong enough.