Do You Need Back-Up Iron Sites on Your AR?

Guest post by Jay Chambers

Whether you’re interested in building or buying your own AR-15, there’s one common question among AR enthusiasts. Do you really need back up iron sites for your rifle? This question applies to those who are already running optics.

If you don’t have any optics at all, then yes, you do need sights. However, if you already have iron sights, do you need a backup, or can you get by without them? It’s a very personal question that may have a unique answer. Many times, it comes down to you, what you shoot, and which gear you decide to run.

The Primary Reason Behind Back-Up Iron Sights

It all boils down to one thing: having a back up in case your primary sights fail. The primary reason why some shooters choose to equip their rifles with back up iron sights is in the event that they have trouble with the sights they normally use.

Iron sights are a bit outdated because of the advances in optical gunsights these days. The latest generation offers a lot of advantages over the traditional iron sights we all used to use. Because of this, they’ve moved to a backup role.

What’s interesting is that because iron sights play a backup role these days, there’s been an explosion of aftermarket back up iron sights for AR-15 rifles. Manufacturers are making a killing off of marketing them as backups.

Back up iron sights, or BUIS for short, are very popular among flat top ARs and there are plenty of models from which you can choose, according to your budget. The term BUIS refers to any iron sight on a rifle that’s already fitted with a primary optical sighting system.

These backups come in two configurations. They are either fixed, or they flip up and down as needed. Fixed back up sights aren’t as popular, because they get in the way of the primary optics already in place. However, they’re always ready for use and can be used in the front or the rear.

Flip-up back up sights rotate out of the shooter’s sight plane when they’re not needed. They have to be raised before use. You can use these on the front or the rear as well, and you can also combine fixed or flip-up sights according to your preference.

Pros and Cons of Fixed Models

The primary advantage of a fixed back up iron sight is that they are simpler and more robust. They don’t have to be deployed, so they offer quicker action if your primary sight fails. Even if the primary optics are still in use, you can use the BUIS as well, sometimes offering increased accuracy.

However, they take up some of your field of view and they can snag. Some shooters find that these types of BUIS are in the way and they don’t want to use them all the time. Plus, if they’re in the way, you have to use more care not to snag them on things if you’re not paying attention.

Pros and Cons of Flip Up Models

One of the primary benefits to flip up sights is that they fold conveniently out of the way when you don’t need them, removing them from your field of view if you’re using a non-magnified optic. If you’re using a magnified optic, they rest beneath it.

Folding these away reduces the chance of it getting caught on something, so you don’t have to worry as much about them being in the way for several reasons.

However, they’re slower to action because you have to fold them out of the way when you don’t need them, or flip them up prior to use. The manual deployment adds complexity and weakness to the design, although it is convenient in some cases.

Things to Consider Regarding Back-Up Iron Sights

There are a lot of BUIS designs and plenty of manufacturers, but there are some things to consider if you’re thinking about installing some backup iron sights on your rifle, the first of which is, will you ever use it?

You already have a backup

If you have several rifles, you may find that you’d rather use one of those as a backup. If you never travel with only one of your rifles at a time, you’ll never be without a backup and you may not need to install back up iron sights on any of them.


Consider the design of the BUIS second when deciding which to install. Because their primary use is as a backup, the only time you’ll likely be using it is if your primary optics fail. That means your rifle has suffered some sort of impact that was hard enough to break your scope.

In that case, you want a back up that is rugged enough to survive this impact. You want a design that’s well made from materials that are strong enough to attach securely without breaking.


The simpler the better when it comes to an emergency sight. When you’re using this in an emergency scenario, that means you’re not using it all that often. Spending a ton of money on something you’ll (hopefully) rarely use seems silly.

Elaborate windage isn’t necessary or realistic, especially for a rear sight. Instead of large, A2-style windage knobs, consider an A-1 style dial with a low-profile knob or a positive lock. They’re less of a liability in the field.

It’s also highly unlikely that you’ll need elevation adjustments. If you’re using it for emergency use at high-velocity, you’ll only need a small amount of holdover, meaning you shouldn’t need a separate elevation adjustment system on your back up iron sights.

Instead, you can use a simple, L-shaped, dual-aperture flip-up sight. It’s likely sufficient for your use unless you’re headed into combat, which let’s hope is the exception and not the rule for most.


Proper installation is essential for your back up iron sights because of the firing vibrations of your rifle. This impact tends to loosen bolts over time, so you’ll want to check it frequently, and ease of installation will help you out in the long run. Cleaning the threads and using the proper amount of Loctite will help prevent this.

Final Thoughts

There are a lot of advantages and disadvantages to the different types, so consider these suggestions first before making your ultimate decision.

The most important thing you can do is evaluate your personal use, needs, and desires carefully before deciding which back up iron sights will work best for you. With the number of options out there, you’re likely to find something that fits your budget with no problem.

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