Need Help with Screw Removal.

[Renji]

I decided to tighten up my stock lock for my KMP9. There I figure out that I have accidentally broken the screw completely off. This screw was sunken in and I can't seem to have any ideas how to get it out and the part is almost impossible to get now. So I need an idea about how to take the broken piece out of the stock clamp to get my stock back into working order. Here's a pic.

the screw is without a head and is sunken down about a millimeter or two. It's the shiny part inside the well of the screw hole. Question is... How do I get it out without drilling it and messing up the threads.
btw, this is taken with a phone camera. Love this quality