I'm not using the FFII, I'm using the III. I used the factory rail with a American Defense Quick detach base. I used it with out a comb raising kit but decided I didn't like holding my head up so I rigged up a some card board and mouse pads to get me through the season, nut next year I will try a aftermarket comb kit from someone. If I had to do it all over again I would just have a 336 base drilled to match the holes on my gun.