On 9/28/2011 2:47, Phil Kangas wrote:
The set screw of interest in this thread is
obviously not stainless! It is
rusted in place.

Stainless will also rust, just a different "rust"..
Happens especially easily when the body is normal
steel and a stainless fastener touches the steel body.
Anybody using same tools for normal steel and stainless
knows how easy it is to get rust spots to stainless..

Still, propably a normal carbon steel setscrew..

One neat drilling solution is to used the normally
ground drills that are made like masonry drills - with
a tungsten carbide (or such) insert.. These will
drill quite hard materials..