According to keglidd :
Thanks All,
The remington masonry gun gets my vote - not too much cake, and easy enough
for me to handle. I'm just framing in a small closet off to the side of the
HVAC room, and this is perfectly workable.

I'm just handy enough to be dangerous.

You'll find tapcons a lot cheaper/convenient than buying or renting a
masonry gun for a small job like this.

You can buy a pack of 10 or so tapcons with the proper drill bit
for $10. A hammer drill is best, but a regular one will work
albeit slower.

Put the board in place, drill right through into the concrete,
and then drive the tapcons.

If this is a slab on top of earth (basement floor, garage floor
etc), wrap the bottom half of the lumber with heavy plastic - use
vapor barrier if you have some. Lumber on top of concrete frequently
wicks moisture (concrete is porous), and without protection the
wood will rot.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.