What are you doing with it just plinking, some type of competition, hunting?
I'm using a FX9 with a 16" barrel and a Burris fastfire 3 for multigun shoots at a couple local clubs, shooting the cheap American eagle 115 fmj ammo.
I zeroed it at 92yrds (both clubs have only 100 yrd range and the stages start out Infront of the covered firing line)
Which works out really well for me its about +1.1 at 25yrds and about -1.1 at 100 yrds and about +2 at 50 most of the steel plates are 6 to 10" I can pretty much put the dot anywhere on a plate and get a ding.
Max pbr on a 6" steel plate is about 155yrds