Compared to red dot sights, iron sights are designed as a physical alignment system utilizing the naked eye. It is a device that operates well under ambient lighting, and it is also a device that won’t fail you for battery/electrical issues, because it doesn’t need batteries! We currently use iron sights as our backup sights most of the time, and you know, plan B is almost as important as plan A. So once you have chosen your primary optic, consider outfitting your rifle or shotgun with iron sights, better safe than sorry! Now, it’s time for you to learn how to adjust iron sights!
Meet your iron sights: Open sights, Aperture sights, and Flip-up sights
Before we jump into how to adjust iron sights, we should know more about them. What is their feature, when is the best time to use them, or which suits you the best? Below we introduce the 3 most common iron sights, open sights, aperture sights, and flip-up sights.
The easiest design: Open sights
Although not the most efficient sighting system available, open sights tried and can truly be very effective. This is made apparent by arguably the most successful assault rifle of all time, the AK-47. The U-Shaped alignment system can provide reasonable accuracy out past 300 yards.
Open sights are also considered a more reliable system under adverse weather conditions such as rain or snow. However, it is less precise than the peep sight and is more prone to alignment error. You won’t be able to focus your vision as good due to the lack of a pinhole that increases your depth of field.
When using open sights, accuracy and low light capability will also take a hit. If you choose between the two, a peep sight will almost always better serve you than open sights would.
The most effective on rifles: Aperture sights
There are 2 kinds of aperture sights, the ghost ring and the peep sight. The most obvious difference between them is the diameter of the rear sight. Ghost ring sights have more expansive space, allowing more lightning, offering advantages in low light and close quarters. On the other hand, the target aperture sights have a smaller space for lightning and a reduction of parallax, and it tends to be more precise.
Ghost Ring Sight
The ghost ring sight is a quick alignment tool simplistic in design that performs well at close quarters and low light shooting. Iron sights, in general, can be challenging to use in the dark regardless of the size of your rear aperture. However, the enlarged hole does help with the light transmission in a low-light scenario. It will also aid you in quick target acquisition. It is important to note that you should not focus on the front sight post with ghost rings as you would with peep sights.
When using ghost rings, focus on your target instead of your front sight post. Your front sight will appear blurry, but this will not hinder your performance when using ghost ring sights at their intended ranges. Not doing so will negatively impact your shooting and make it difficult to see your target.
Keep in mind that ghost ring sights will have a higher degree of parallax. Centering your front sight post is of greater importance than the peep sight due to the increased risk of alignment error due to the raised rear aperture size.
Target Aperture Sights
Peep sights have been a staple in the history of the American Rifleman. The small rear aperture allows for precise shooting in both short and long-distance. It excels in conditions where ambient light is available. The peep sight design also provides minimal alignment error afforded to the shooter. Meaning you will maintain a reasonable amount of accuracy even if your front sight post does not appear to be dead in the center of your rear aperture.
The peep sight will also allow you to focus on the front sight post while maintaining relative clarity of your target. As a result, the best method of utilizing the peep sight is to focus your eye on your front sight post. Your target will appear slightly blurry, but this will allow you to maintain a higher degree of accuracy.
The best option for your backup sights: Flip-up sights
Nowadays, flip-up iron sights are the most common on the AR platform. They benefit from running flush with your rail when not in use while also taking up a minimal amount of rail space. This allows more ideal sighting systems such as red dots and scopes while also withholding the foolproof mechanical simplicity of a design that rarely fails.
Flip-up sights also benefit from co-witness through non-magnified optics such as reflex and holographic sights. This means that should your optic fail, you need not remove it to utilize your iron sights. Simply flip them up and aim passively through the window of your optic. When using magnified optics, you will need to remove the optic to deploy your iron sights.
Now, how to adjust iron sights?
Adjusting iron sights is not quite as intuitive as adjusting optics but still relatively easy. We can break it into 2 phases: Achieve mechanic zero at home and zero iron sights at the range. But before we elaborate on the process, you should make sure your iron sights are appropriately mounted. There should be no play and should be firmly locked in place atop your rail. Ok, we can head to adjusting iron sights now:
Achieve Mechanic Zero at Home
- First, take your front sight and adjust the sight so that the base of the front sight post is flush with that of your sight well.
- Next, max out the windage adjustment, dial in either direction until it comes to a stop.
- Then, proceed to count the number of clicks it takes to max out your windage in the opposite direction from end to end.
- Finally, divide the number of clicks by 2. If it took you 40 clicks from side to side proceed to adjust your rear aperture 20 clicks to center and achieve mechanical zero.
Zero iron sights at the range
Once you are at the range, you will need to pick your zeroing distance. 25 and 50 yards tend to be the most common. Click here to learn zeroing distances in depth. Find a stable shooting platform to conduct your shots once you have your target set up at your selected distance. Now we can start to zero:
- Step 1: Fire a 3-5 round group placing an emphasis on proper sight alignment, stability, and trigger fundamentals.
- Step 2: Observe your point of impact and how it relates to your point of aim.
Here are some tips for you when you are zeroing at the range:
- Using paper that has a grid with 1-inch squares is very helpful when evaluating what adjustments you need make.
- For flip up irons, rotating your front sight post clockwise will raise the point of impact of your bullet; Rotating counterclockwise will lower the point of impact of your bullet.
- For elevation, turning your windage dial clockwise will move your point of impact to the right; Rotating counter clockwise will move your point of impact to the left.
- Be sure you know the adjustment value of your iron sight before you begin making your adjustments.
Using these values, adjust accordingly so that your point of impact coincides with your point of aim. Once this is done…. BAM! You’re Zeroed.
It may be helpful if you document what adjustments were made from your starting mechanical zero. This way, if you must make further adjustments for different ranges and conditions in the future, you have a reference point to reobtain this same zero without repeating the process.
Using iron sight as a backup is crucial. Let me tell you a story…
While serving in the Marine Corps, I was fortunate enough never to have to resort to iron sights myself. However, I did observe an instance in which one of our machine gunners temporarily had to use iron sights.
His rifle became detached from his body when fast-roping down from a V22 Osprey. As a result, his M4 took about 30 ft to dive straight onto some old concrete. The Trijicon Acog he was using completely broke. That’s right…. The legendary little tank of an optic met its match.
The backup iron sights he attached to his m4 were utterly functional and supported him until he was able to get a replacement optic. So, no matter how tough you think your optic is, it is still prone to failure. Nevertheless, carrying iron sights can potentially be the difference between being in or out of the fight.