Chuck,
I followed your original post with much interest, and at that time I thought I might have drilled the hole first, and set-up the tenon angles to match the hole angle. But I'm used to drilling first, and thankfully, have enough to do around here without getting in to repairing stocks. (I'm rust bluing a two barrel set for a custom project at the moment.)
I do look forward to seeing the results after drilling. You don't have much drill depth to go with the way you have set it up.
Think I hear the water boiling....
Steve
