Check out this video form LoneWolfUSMC 8541 Tactical.
http://www.youtube.com/watch?v=aoW5bHQqgis&list=SPABEFDD83DF9BA2A4
I applied bedding material to both the front and rear and then tightened the front but just used the rear screws as guides for the rear of the base, but did not tighten...