I have one of these: http://www.tylertool.com/drilldoctor8.html
And it has kept me from pitching countless masonry bits as scrap steel.
The smaller masonry bits only seem to last a few holes.
There is nothing as nice as a sharp new factory bit for any job though.

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/showpost.php?p=831799&postcount=13
http://www.peachparts.com/shopforum/showpost.php?p=831807&postcount=14