These nails are not meant to sink even with the wood.  If your framing is done right these nails should provide nothing more than bump resistance for the wall.  Your framing should be very snug to joists and let the wood get itself straight. Meaning that the nails at the plates don't do much.   

When I am framing a basement I usually put in 3 per 8' board.  I would be happy with your depth and would want it no more than an inch in concrete.  Meaning the wall isn't going any, but if someone needs to take the wall up they can do so with a prybar or hammer.  If your bottom plate doesn't wiggle and you can kick it you are good.