Last couple of rifles, I installed the pipes when forearm was still square. To me, its easier to get the pins straight and where I want them since I'm using a drill press. Any little bit of blowout of wood will not show once I shape the forearm. The only issue is if you leave too much material on the forearm, drill bit may not be long enough, I like to drill as far as possible thru the stock from one side. I set up my drill press with a sharpened pin mounted right exactly below the drill bit, spots marked on stock both sides, one for the pin and the other for the bit to enter. I usually do a lot of butt stock work prior to this point, easier to hold rifle @ forearm.