How to Zero an M4 Iron Sights

The M4 5.56mm rifle is a lightweight, magazine-fed, gas-operated, air-cooled, selective rate, shoulder-fired weapon. It also has a collapsible stock. Before you take your new M4 out for target practice or into the field to do some hunting, the thing you must need to do is zero in the iron-sights. So, to get the most out of your rifle, you need to know how to zero an M4 with iron sight. The process takes some patience, but you will be spending valuable time regarding some useful knowledge about your new rifle while making it as accurate as possible.

Functions of Front and Rear Sights

When it comes to zeroing the iron-sights on your AR-15, it’s important to understand what the front and rear sights do. The front sight handles elevation, or how high or low the point of impact is compared to the point of aim. The position of the rear sight will determine the windage, or whether your shot will hit to the left or right of the target.

Step 01: Mechanical Zero

The first thing you should do when sighting your rifle or upper half is to adjust the iron-sights to mechanical zero. At first, you have to rotate the front sight post up or down until the base of the post is flush with the sight well. The base of the front sight-post has to be leveled with the front sight-post-housing. Then you have to lower the front sight-post by turning it clockwise. After finishing the front sights let us move on to the rear sight.

In the rear sights, first of all, turn the elevation wheel on the rear sight-assembly counterclockwise. Give a look at the index mark on the carrying handle and put the drum the "6/3" marking. Most sights on an M4 have both a large and a small aperture. The large aperture is used for close up shooting has a line that can be used to align it with hash marks along the bottom of the rear sight. If the aperture doesn’t have a mark, simply rotate the windage knob until the aperture is all the way to the left or right. 

Having finished with that, turn it all the way in the opposite direction, count clicks as you go. Divide the number of clicks by two to determine the center of the rear sight. Then, don’t forget to move the rear sight that number of clicks from one of the sides. 

Step 02: Zero to the shooters

Once the iron-sights are zeroed you can start adjusting them for accuracy. 

First Load the weapon with five rounds. Set a zero target as your need, I will recommend you to set your target at 25 meters because at 25 meters, each square is 1 MOA wide and tall.

That makes it easy to work your sight adjustments; meters from the firing line. Fire five rounds of ammunition at the center of the zero targets. Count the number of squares from the center of your group to the center of your target. Note the number up or down, and the number left or right. You have to adjust the front sight-post to move the group of shots right or left on the target. Also, don’t forget to adjust the elevation knob on the rear sight-assembly to raise or lower the group of shots on the target. Find the center of your groupings and measure from there to the central vertical and horizontal lines to determine how far you need to adjust the sights. If the shots appear all over the target and aren’t in groups, focus on the shooting fundamentals until you achieve groups. To move your groupings to the left, turn the windage knob on the rear sight to the left and to the right to move your grouping to the right on the target. Looking from the top of the sight, the front sight post will need to be turned clockwise to raise groupings and counter-clockwise to lower them as they appear on the target.

Basically, if you want your shots to appear on the target you will want to move the rear sight in the direction, and front sight in the opposite direction.

Confirm Iron Sights Zero

Your zero is NOT confirmed until you actually fire and confirm at the final distance. It’s a common mistake to zero at 25 meters or 50 meters and assume that you’re also good to go at 300 or 200 meters, respectively. But that’s wrong. The 50/200 and similar type zeroes are nothing but a myth. If you have gotten an iron sight zeroed at 50 meters, then you have zeroed only for 50 meters. If you want to be zeroed for 200 meters, then you need to put your target out at 200 yards and finalize your zero.

Be Aware of Windage

When confirming zero at ranges past 100 meters, the effects of the wind needs to be considered and acted upon, if necessary. If you confirm a zero at 300 meters on a windy day, and then you fire the weapon at a later date in different wind conditions or no wind at all, the impact will change. Remember, zero is a combination of factors that include the conditions. If you zero your rifle in a 10-mph crosswind, then that’s your zero. If the wind isn’t there the next day, then your conditions have changed.

Most people zero their sights for a baseline and then compensate for any changes.


  • Wear necessary hearing and eye protection while shooting.
  • Make sure the weapon is safe and clear and functioning properly
  • Never fire a weapon unless all shooters are of the range and behind the firing line
  • Make sure all firing has stopped before walk forward of the firing line.

Final Words

Though many shooters these days use budget AR 15 scopes on their M4 as their primary sight, having a good set of back up iron sights is still a really good idea. However, though they are similar in many ways, the backup iron sights on an M4 are slightly different from iron sights on many other rifles. Hope the article was helpful and worth reading for you.


Hey I’m Elizbeth Smith. I’m associate aspiring businessperson, sure-fire author and blogger. I like to write about, home improvement, outdoor,personal finance, art, fitness and lots more.

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  • Ermenegildo Napolitano
    How mich does every click adhust m4 front sight?
    5 months ago
  • Roosa
    How to 25 meter zero an m4 iron sights?
    1 month ago
  • fosco
    Do you adjust elevation rear iron sights for 200, 300 shots?
    1 month ago
  • lea
    How to adjust m4 iron sight?
    26 days ago
  • mike
    How are iron sighgs zeroed?
    17 days ago
  • Edoardo
    What m4 barrel changes iron sights?
    1 hour ago

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