Solid Hardwood, Engineered and Laminate Flooring - proper gapping under baseboard?

I am installing mohawk laminated flooring in my L/R,Hall and entry and was wondering if my baseboards dont sit all the way down on my floor do to just painting 2 yrs ago (could see paint lines if I go flush with floor) can i put quarter round at bottom of base board and attach them with a brad/finish nailer. At present time i have a air finish nailer but was thinking of purchasing a cordless. Someone was telling me if i shot the quarter round in make sure I dont shoot down to press the quarter round into floor(nailing into base board) other wise it could not expand properly.
Any suggestions would be greatly appreciated and I am almost to this point of my project.
Thanks,
JeffMO

Sounds like a plan to me. I use ¼ round all the time, because my clients don't want the baseboards removed.