Best AR-15 Backup Iron Sights (BUIS)

Hey, that's a nice optic you've got, there. But what happens when the batteries die or something smashes the glass?

When the worst happens, backup iron sights (BUIS) are worth their weight in gold. There are lots to choose from, and it can be hard to decide which ones are right for you -- or if you even need them at all.

Today, we’re going to look at some of the best AR-15 backup iron sights we've used.

So get ready to dust off those old-school marksmanship skills!

Backup Iron Sight Comparison Chart

How We Chose the Best AR-15 Backup Iron Sights

We’ve shot thousands of rounds and spent hundreds of hours with guns of all kinds between our hands-on reviews, shooting events, and firearms from our own personal collections.

Input from this article came from both writers and some of the full-time staff at Pew Pew Tactical. We have had hands-on experience with almost every iron sight on this list.

We selected these sights based on reliability, durability, features, and value.

Best AR-15 Backup Iron Sights (BUIS)

1. Magpul MBUS 3 - Editor's Pick

Editor's Pick

Magpul MBUS 3

$100

at Magpul

Prices accurate at time of writing

$100 at Magpul

Brownells (see price)

MidwayUSA (see price)

Primary Arms (see price)

Specs

• Material: Polymer
• Adjustable for Elevation: Front only
• Adjustable for Windage: Rear only
• Orientation: Flip-up

The Magpul MBUS 3 is an affordable and effective backup sighting system for the AR-15 platform.

Magpul’s front and rear sights are built from lightweight and durable polymer that can handle any wear and tear you throw at it without any major issues.

With the Gen 3 MBUS, Magpul reduced the overall size of the sights they lay nice and flat. Ambidextrous buttons deploy each spring-loaded sights automatically.

The front sight features toolless elevation adjustment and a rectangular front post that lets you choose hoe thick you want it to be in your sight picture. Use the wide side for speed, or the skinny side for precision.

The rear sight has a knob to adjust windage, and dual apertures. Again, use the large one for speed or low-light environments, or the small one for daytime accuracy.

As long as you’ve got a Picatinny rail system on your gun, you’ll have no problem mounting these BUIS in minutes.

Most importantly, the MBUS 3 system is super affordable! It's inexpensive and it works -- no wonder so many people use it.

What's your take on the Magpul MBUS 3 sights? Give it a rating below.

2. FAB Defense Flip-Up Sights - Simplest

Simplest

FAB Defense Flip-Up Sights

$90

at BattleHawk Armory

Prices accurate at time of writing

$90 at BattleHawk Armory

OpticsPlanet (see price)

AR15 Discounts (see price)

Specs

• Material: Polymer
• Adjustable for Elevation: Front only
• Adjustable for Windage: Rear only
• Orientation: Flip-up

Straight from the guys that make stuff for the Israeli Defense Forces comes the FAB Defense Flip-Up Sights.

These are lightweight polymer sights like the Magpul MBUS 3, but they don't have an internal spring. That isn't necessarily a bad thing.

It's rare that you need to deploy your BUIS, and I actually like FAB's system since you're less likely to unintentionally activate the front sight if you use a forward C-clamp grip on the handguard.

The view-through is great, and the sights are very easy to adjust. Use the front sight to change elevation, and the rear sight to change windage.

Overall, these are a great alternative if you don't want or need the spring-loaded system of the MBUS.

3. Troy Micro HK-Style Sights - Best Value

Best Value

Troy BattleSight Micro HK-Style Flip-Up Sights

$140

at BattleHawk Armory

Prices accurate at time of writing

$140 at BattleHawk Armory

GrabAGun (see price)

GunMag Warehouse (see price)

Specs

• Material: Aluminum
• Adjustable for Elevation: Front only
• Adjustable for Windage: Rear only
• Orientation: Flip-up

If you’re looking for something that’s sturdy and dependable, Troy Micro HK-Style BUIS are strong enough to take a lickin’ and keep on tickin’.

These low-profile iron sights are under 1.5 inches in length and only weigh a couple of ounces. You'll forget they're even there.

We specifically like the HK-style variant of these sights, which uses a round front aperture that is similar to the front sight you would see on an MP5 or G3. This aperture style feels like it crowds the sight picture less.

This setup is an excellent alternative for anyone who’s not so keen on polymer sights and wants something actually made out of metal – as the name iron sight implies. It's not too expensive, either.

4. Magpul MBUS Pro - Best Metal

Best Metal

Magpul MBUS Pro

$183

at Amazon

Prices accurate at time of writing

$183 at Amazon

OpticsPlanet (see price)

Brownells (see price)

Specs

• Material: Steel
• Adjustable for Elevation: Front only
• Adjustable for Windage: Rear only
• Orientation: Flip-up

There is no question that the Magpul MBUS family has been considered the industry standard for some time now, but the Magpul MBUS Pro is awfully nice if you have a few more bucks to spend.

Some people just aren't comfortable with the thought of polymer sights. Yep, these are steel -- not polymer or aluminum. The MBUS Pro sights are built to withstand the harshest conditions while remaining easy to use.

Both the front and rear sight have low-profile knobs that allow for toolless adjustment for elevation and windage, respectively.

If you want a set of ultra-tough, duty-ready, flip-up iron sights, these are the ones to get.

5. Surefire Rapid Transition Sights - Best Offset

Best Offset

Surefire Rapid Transition Sights

$179

at OpticsPlanet

Prices accurate at time of writing

$179 at OpticsPlanet

MidwayUSA (see price)

EuroOptic (see price)

Specs

• Material: Aluminum
• Adjustable for Elevation: Front and rear
• Adjustable for Windage: Rear only
• Orientation: Offset

All these folding BUIS are slick, but what if you want something more capable? The Surefire Rapid Transition Sights don't cut any corners.

These are offset sights, which means they mount to the top Picatinny rail but stick out to the right at a 45-degree angle. That adds potential snag points to your AR-15, but they're never out of service and you can switch from them to your optic as fast as you can tip your hands to the left.

More importantly, this is the only system here that has a fully adjustable rear sight. If you look closely, it's the exact same assembly that's on the old A2-style carry handle. That means you can dial for wind and distance on the fly.

Yes, they're expensive, and yes, they're kind of bulky. But if you want something fast that can accurately engage targets out to several hundred yards, these are the backup iron sights for you.

How to Choose the Best Backup Iron Sights

Backup iron sights on your AR-15 are like airbags in your car; you don't need them until things go seriously wrong. Then, they can save your life. Let's figure out how to pick the best AR-15 backup iron sights for you.

Materials

We call them backup irons, but they typically come in polymer, aluminum, or steel construction.

Polymer is lighter and less expensive than metal. On the flip side, metal is stronger and usually machined to tighter tolerances.

Both will get the job done. If you're only going to be using your backup sights in close-quarters, down and dirty shooting, polymer is perfect. Don't spend more money than you need to. If you want to stretch shots out further without an optic, look for steel sights with some degree of adjustability.

Orientation

Backup iron sights are meant to work with a red dot or scope installed. There are three main styles, and it's up to you to decide which one you prefer.

Some align with a red dot so you can use either without moving anything -- including your head. This is called co-witnessing. If your red dot goes down, just shift your focus to your irons and keep plugging away.

Most backup iron sights lay flat when you don't need them, then flip up when you do. These are good for keeping your AR-15 streamlined but you'll have to take the extra step to deploy them if your optic fails. Oh, and don't forget to test them to make sure your optic doesn't block the view.

Some people prefer offset irons. These hang off your AR-15's top Picatinny rail at a 45-degree angle so there's no interference between them and your optic. All you have to do is slightly rotate the firearm in your shoulder pocket to use them. This is especially useful if you're running a DMR-style setup with a higher magnification range. Use the scope for long shots, and switch to irons for anything up close.

Adjustment

If you're concerned about landing hits on a standard silhouette target inside 50 yards, you can probably slap most backup iron sights on your AR-15 and expect them to be pretty close out of the box (but always check).

If you want to use them in place of your magnified optic, adjustment is key. Specifically, look for a rear sight that lets you dial for elevation and wind. Once you know how to use these features correctly, you'll be surprised how effective they are.

Why Trust Pew Pew Tactical

This article builds on the work of former Pew Pew Tactical author Brandon Harville. Brandon is an avid hunter, skeet shooter, recreational shooter, and gun collector with experience in evaluating gear like BUIS.

Editing this article is Scott Murdock. Scott is a Marine Corps veteran who competed and qualified as a rifle and pistol expert while in service -- with iron sights, thank you very much. In addition to shooting, Scott has written for a variety of publications, testing, researching, and evaluating guns and gear. He brings that knowledge and skillset to this article, editing and fact-checking for accuracy.

Editor-in-Chief Jacki Billings runs our experienced team of gun reviewers. She is a member of the Society of Professional Journalists, ACES: Society for Editing, and the Professional Outdoor Media Association. Jacki has a bachelor’s degree in Mass Communications and has worked as a media professional for close to 20 years, specializing in gun media for almost 10 years. She uses her extensive professional journalism and editing experience to set testing protocols and editorial standards.

Final Thoughts

Now that we’ve covered the importance of backup iron sights and looked at some good ones on the market, you’re ready to upgrade your AR-15.

But remember, BUIS are no good if you don't get them sighted in. Check out our guide on how to zero iron sights.

Do you have backup iron sights on your rifle?  Let us know in the comments. Want something more advanced? Check out our Best AR-15 Scopes & Optics!

Latest Updates

• March 2025: Removed the Ade Advanced Optics Offset Sights. Added the Surefire Rapid Transition Sights and comparison chart. Updated supporting content.
• October 2024: Removed Magpul MBUS Gen 2. Added Magpul MBUS Gen 3 and Magpul MBUS Pro sights.
• September 2023: Removed discontinued models.