A word of warning when using fusion it Bonds by which I mean if you get some on the inner side of the frame and try to get it off it kinda wants to take the original plastic with it, just letting you know to save you some trouble. Still damn good paint.
Make sure that the little hook under the trigger is hooked to the spring under it, secondly make sure that the whole turret assembly is put together properly, and lastly the trigger itself is laying in the frame right otherwise it slips "on and off track if you will".