I am not a gun builder, just a hobbyist who has build several rifles and one pistol. A good friend of mine showed me a trick for drilling the barrel pin holes through the stock and under lug. Once I have the under lugs installed I set the barrel up in my drill press vice with the top flat flat against the inside jaw of my vice, then I line the drill, of the correct size for the pins I am using, up so that the bit just misses the bottom barrel flat, and is centered in the lug lengthwise. Once this is all set up I mark the barrel so I can line the drill bit back up with the lug at the exact same spot. Once all of this is set up, I remove the barrel from the vice, install it back in the stock and then remount it in the vice with the top barrel flat again against the inside jaw of the vice, and the bit lined up with the mark on the barrel, then I simply drill, slowly through the stock and the lug. I make sure my bit is good and sharp. I have used tape on the underside of the stock which helps some to keep the bit from busting out extra wood as it comes through on the underside. I've done this several times now and never had a problem, holes always line up nice all the way through. I have had to have someone give me a hand balancing the rifle in the vice while I do the drilling. I know there are other ways, I've studied them, just haven't used any other than this, and all I can say is it works for me, may not for others.