Rear sight on '1'. Check front sight drum as detailed above. At 25 yds, aim at the bulls eye but adjust the point of impact for 1" low. Now at 50 yds, you should be pretty much on the center. At 100 yds you may be a few inches high or low or off to the left or right, so here is where you make your final adjustments. Now the other positions of the rear sight are more or less indexed, but leave it on '1' unless you are shooting at more than 150 yds.
In order to achieve these results, you have to sight in from a rested position. You can't zero a rifle from your elbows or standing. Those positions are for general shooting AFTER sighting in. The reason is, most shooters can't shoot a small enough group off hand to be meaningful in adjusting the sights.
Generally, this is what's wrong with your shooting, assuming nothing is wrong with the rifle - you have to shoot from a rested position, take your time, load only three rounds at a time and take 30 seconds to shoot them. You have to have good trigger technique and be able to concentrate for 15 seconds at a time to get the gun zeroed. Once you do that, you can blast away all you want with the confidence that when you miss, its you, not the equipment.