No need to agonize over this. With a carbine gas system you've got a sight radius of 14.5 inches. With a Magpul rear sight and 14.5in sight radius, one click of the rear sight moves POI about .75 inch at 100 meters.

You're shooting at 50 meters. That makes it two clicks to move POI .75 inch. You're shooting seven inches off. That would be 18 clicks at 50 meters. Count your clicks at home. Go to the range. You'll be on.

If you have lost track of where you were... fire a few shots to see where you are. Use the above formula. Move the sight all at once. No need to fool around a click or two at a time for initial zero. You can fine tune afterward.