Slow your drill speeds and use lots of cutting oil and use a drill press, drill it with a 1/8 drill bit, they are a pain and do eat up bits. I usually have to freshin up the bits a couple times with the drill doctor. What kind of penetrating oil are you using? Only use kroil and soak it for a week, soak it to where gravity will pull the oil down into the barrel pin hole, all it takes is one good smack dead on blow and it will move. I use a four pound hammer, vise grips to hold a punch, a trusty friend to hold the vise grips and all my might to smack that fucker. Another trick i use is, with the barrel pin soaked in kroil for a week, right before i start pounding, i take a propane torch and put heat on the oposite side of the trunnion with a small puddle of kroil on the other, what will happen is the heat will draw the oil down around the pin which will aid in removal. Drilling is a last resort, they do come out it just takes patience. If its messing with you walk away, have a smoke then come back to it later, that usually works for me.