[DeTomaso] [NPC] Selecting air drills

[Mark McWhinney]

I am trying to drill some holes into concrete slab (garage floor) for some
anchor bolts.  My battery powered drill which has served me well for years
is not up to the job.  It gets part way then jams up.
 
This is a good excuse to go get an air drill.  The question is what to get.
The 1/2", pistol grip drills are all rated about 4 or 5 CFM air consumption
but have free speeds of 500 to 2,500 RPM.  I assume that they are the same
under the covers but have different gearing for the different top-end
speeds.  Since I need more torque than speed, should I go for the low-speed
drills?  (Most manufactures specify their free speeds but not their torque,
hence the question.)