In years past, gun drilled bolts were legal. The issue is really not that the bolt is drilled, but more it is how much. It is one thing to take a 3/4 inch diameter bolt and drill about a 1/4 out of the center. .750-.250 leaves .500, which means you have .250 wall thickness. In that instance, it actually gives a bit of strength to the bolt being a tube rather than a solid. But, 1/4 inch was OK, so lets put on the racer hat and decide a few more ounces can be saved if we drill it out a half inch. .750 - .500 leaves .250, or a 1/8 inch wall thickness. And that is the shank. remember the entire bolt is drilled. Lets go out to the threads and measure the wall diameter in the thread valleys. It is going to be less than the 1/8 inch. So if you look at the bolt in question, it is significantly drilled. This leaves a potential for the threaded area to crack, break, and release the bolt, giving it a chance to vibrate out. This has happened. That is why every SLM sanctioning body in the country has a no drilled bolt in the suspension clause, and some go so far as to ban them over the entire car. As for a DQ over one bolt, where do you draw the line? If you are on this forum, you have something to do with racing. OK, one bolt, we'll let it slide. you will say, well, its only two bolts. then only three bolts. You all have seen a scenario played out like this.