My new Vortex was not centered or mechanical zero when I got it new. I found a video on Youtube that showed how to center your cross hairs using a mirror. Basically if you put the objective end up to a mirror and look through the scope, you'll see two sets of cross hairs. Adjust the turrets until you see one set. Also I used a scope mounting kit from Wheeler. It helps to ensure that the rings are aligned true and has a lapping bar and compound to remove some of the surface of the rings to make a perfect alignment. The kit I got came with a in/lbs torque wrench and tips. If after ensuring your scope is truly centered and mounted properly your still grouping way off... remember that Vortex has the VIP warranty. If there is something wrong with the scope, they will fix it or replace it.