Maximum range is when the cant of your scope base has the barrel obstructing your view. Find out when your bullet goes through about 1300 fps and set up some gongs at that range and a bit further to see how they do when going subsonic. The drag curve may change a bit and cause you to require more drop adjustments past that range but otherwise your good to go. I shoot the 168 Berger hybrid in my .308 and it goes subsonic just fine. I have had it out just shy of 1200 yards. The drop is consistent but the wind sure makes it interesting.