Bob Engelhardt fired this volley in
:

http://home.comcast.net/~bobengelhardt/drill2.jpg

Bob, I have four "star drills" in various sizes, none of which are fluted
for twisting like yours, but none of which have carbide tips, either.

The star drill has been the standard for decades for penetrating block
walls precisely and easily without a lot of spalling on the downwind
side. Just a gentle "tap-tap-tap-turn, tap-tap-tap-turn" and the hole
virtually makes itself.

The twist version allows you to clean out a blind hole, which a common
star drill cannot do.

LLoyd