Sometimes people really get carried away with scope magnification and think that it will increase your accuracy.  Well try taking a 5.5-20×50 scope to the range on a 90F day and tell me if you can even see X on a paper target at 300yds.   Anyone with experience will know that a mirage will void you scope magnificatioin and actually make it very difficult to make pin point accuracy.   A mirage is a constant wave of distorted light due to heat rising and you might be better off with lower magnification or Zero magnification.  Most Trijicon ACOGS are really meant for medium range engagements.

Recently I got to the range and tried out some of the newer green reticle ACOGS and the first one I tried out on my Bushmaster XM15E2 was the Trijicon TA11H-G.    This optic is actually a long range optic and might be best suited for a machine  gun,  The Trijicon TA11H-G ACOG has a green horseshoe reticle which for some reason seems to be very popular.  This particular ACOG has a longer tube than something like the TA31F-G