First of all, what caliber are you shooting? If it shoots low with regular factory ammo, then I would suggest you try using a heavier bullet to raise your POI. Often, it'll take some reloading to just raise the bullet impact. Sometimes you get the POI raised but ends up to the right or left. I adjust that by turning the barrel in or out depending on where it needs to go. You want it to go right, twist the barrel in an RCH. You want it to go left, go the other way.
