I like to caution anyone who goes looking for a "sight pusher" to first make sure that they need one. I've seen way too many shooters blame their inability to hit the center of a target on the sights. In many cases it's merely a matter of adjusting grip or the amount of trigger finger used.
If you haven't, try shooting from a solid rest. A machine rest is best but any rest from just a box to a sandbag will help. Make sure that the point of impact is off because of a mis adjusted sight first. Then, one more step. Check out this:
Lots of people that have asked me for help on adjusting a sight have used this chart to correct what they first blamed on the gunsight. You'd be amazed at how much difference just the placement of the trigger finger can make.
Just print this out and use it as a target. It will tell you a lot about your shooting style.