RE: Boomerang Sprint Build Thread!
I was just watching an advertisement, on Cable TV, several days ago, for a Screw Extractor Kit. This particular kit came with bits that had a conical shaped drill that was used to prepare the bolt before extraction. They specifically showed it being used on a bolt where the head had twisted off. Once the conical depression had been drilled into the top of the bolt, the bit was flipped over, slipped into the chuck of the drill, inserted into the depression in the bolt, and bolt was extracted.