I'm thinking it's an "Angle-Eject" and that's just the extractor cut on the breech face...it does look like it's possibly suffered a little abuse, perhaps a case stuck and someone pried it out with a screwdriver...you'd be surprised to learn just how soft the metal is in a good many Barrels and Frames.Do you have any pics of the bolt face where it meets up with that chip. I wonder if there was some foreign material that got caught in between.