I have done just what you are wanting to do. You will have to bore the third hole as you said or if you know someone who can relocate the front mounting hardware on your barrel ( this is what I did, my dad runs a machine shop ) to match the spacing on the forearm. One last note, if your barrel came with the ramrod guide upfront this will need to be removed as the forearm only leaves about 1 1/2" of barrel sticking out. It looks and functions great, the added weight and length are not really noticeable when hunting with it. Good luck