How are most sights so accurate on guns, even though they’re a few inches above the barrel?
Sights are accurate because they get adjusted and calibrated by moving the sight little amounts until the sight is lined up with the shots from the barrel.
They have to be sighted for a certain range. The M16 barrel is pointed up compared to the sights, so if the thing you’re aiming at is too close then your shot will be high. I can’t remember the exact range, but somewhere around 30yds is the same aim as 200yds, as the bullet will come up, pass through the aiming point, then keep arching and fall back into the aiming point. So sighting in will happen at 30 to make sure there’s nothing wrong with the rifle, and then practice at 200 to get wind adjustments.
1. Many sights are adjustable, so they can be calibrated to match the user and the shooting distance.
2. Fixed sights still provide a reference point for you to aim with, though you’ll have to compensate on your own. The sight isn’t “accurate.” It’s a tool to help the user shoot accurately.
3. Most sights (and scopes) have markings etched into them to assist you in compensating for the bullet’s expected trajectory.
A shot is fired and then sights are adjusted so that one shot is in the center of the sight. Now the sights are good for the shot distance that was used to calibrate them. For other distances sights require adjustments. Else you can estimate the bullet drop to longer ranges and do the adjustment with your eyes.
The sights are adjusted carefully so that the rear sight is a tiny bit higher than the front sight so that they point directly to the spot in the distance where the bullet will hit. This only works for specific distances and shootings farther requires aiming above the target.