I always inlet the barrel first then the RR hole. I have not had any problems with a drill wandering for many years and over a hundred stocks. The only secret is careful measuring, drawing ACCURATE lines and then remeasuring everything again. And then rechecking the lines and measurements again. I never drill until I am 100% sure I know exactly where the hole will end up. And yes, I learned that the hard way with a few ruined blanks. A big factor when drilling to prevent drill wandering is frequent and I mean frequent (every 1/4 inch or so) clearing of chips while drilling. If you think you can drill just a little bit more before clearing wood chips, you are asking for trouble. I used to get nervous about it, but now, just by drawing accurate layout lines and exercising diligence in checking everything, I don't give it a second thought. Anything is better than using a pre-carve with those horrible 1/4 inch think webs.