I just pulled a pretty good one. A customer brought in a GEW 98 Mauser action that had been re-barreled to a 9.3x62 with an unknown brand, lightweight, fluted, stainless barrel. He just wanted the stripper clip hump removed and a set of Leupold bases installed. I set my mill up with a chuck and was drilling a pilot hole with a 1/16" bit which, right before I reached my desired depth, snapped. I tried every trick I knew to get all of the pieces out of the hole, but every time I'd try to open up the hole, it would just wipe out the leading edge of the bit. I ended up chucking up an oddball .080 end mill that I had in my box to chew up the bit and then, my wife called me. I forgot where I was at and started drill while watching my depth gauge. All of a sudden, I lost pressure on the handle. Sure enough, I'd gotten distracted and forgot to re-zero my gauge after switching from the last bit to the end mill and ran the end mill all the way through the barrel shank into the chamber, so now, I'm shortening, threading, and rechambering the barrel for free.