Yeah it will. the KAC uses a twist knob on the bottom to tighten to the rail. Essentially, there is a round pin that protrudes as you twist the knob and puts tension on the rail. the exterior dimensions of the rails are the same, but it's the width of the grooves that makes the difference.
http://www.brownells.com/.aspx/lid=10724/learn/Picatinny_Rails__Weaver_Rails__What_s_The_Difference_
Wish they made a short version of this. It was the quickest and most secure grip to put on and take off, when I used to use them.(read- past tense) ;D
might want to check this out:
http://www.amazon.com/ProMag-AAFG03-Archangel-Polymer-Vertical/dp/B0039Y2H64
