I too have a FF2 3x9 with the Ballistic Plex. I have it on a 18" .223 wylde bull barrel. Its all I need, I consistently shoot .4" groups at 100 and the other day with a slight cross wind I shot 3" groups at 200. Using the 2nd dot. You will just have to experiment with your loads, bullet weight, velocity, etc. to get everything right then dont change. If all you are going to do is shoot paper the 4.5-14x is okay. But for me its way to much for anything else. I believe the ideal is 3.5-10
Scoop how do you like that Calvary Lower? My son has some (Bedford County Tactical) I think as soon as I can get some more parts I may build one. The difference in the weight is unreal.