Best Back-Up Iron Sights (BUIS): Sighting System That Never Shuts Off

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Nowadays, red dots and modern optics are all the rage in gun sighting systems. They’re great and all, but are not totally immune to the weakness of all things electrical – they can shut off.

Also, optics usually involve some sort of glass lance that can scratch or even break.

Things can easily go out of hand when your most trusted optic bails on you in a tight spot. I don’t want that to happen, and I bet you don’t want it either. Back-up iron sights exist for that very reason. After all, BUIS didn’t get the “oldies but goodies” without proving reliable over the years.

If you’re looking for time-tested durability, take a look at the top backup iron sights on the market.

Best Polymer
Magpul MBUS Gen 2
  • Dual aperture
  • Spring-loaded flip-up sight
  • Adjustable front and rear
  • Cannot be installed on a railed gas block
$83 Shop NowClick to read my review
Best Budget Buy
Bugleman Foldable Fiber Optic Sights
  • Fiber sights
  • Lightweight
  • Comes with an Allen wrench tool
  • Fitting problems
  • Not for railed gas blocks
$44 Shop NowClick to read my review
Top Pick
Daniel Defense Fixed Sights
  • Holds zero well
  • Aircraft-grade aluminum construction
  • Hardcoat anodized
  • Hig hprice
  • Busier sight picture
$134 Shop NowClick to read my review
Ozark Armament 45 Degree Offset Sights
  • Readily deployed backup sights
  • Military-grade construction
  • Quick optics to irons transition
  • Prone to snagging
  • Needs some getting used to
$34 Shop NowClick to read my review
Feyachi S27 Fiber Optic Iron Sights
  • Aircraft aluminum material
  • Mil-spec hard coat anodizing
  • Allen wrench included
  • No spring for the flip-up mechanism
$29 Shop NowClick to read my review

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Do You Really Need Back-Up Iron Sights?

(from Giphy.com)

The short answer is yes. While they are less capable than a modern optic they do the job very well. You buy them “just in case”, but, at least for me, those cases come up more requested than I like. 

Don’t get me wrong, modern optics are reliable and impressive, and I have a couple of them mounted on my AR-15s. 

A lot of them have backups for when they run out of power. There’s no need to replace batteries often because some already have solar modes on standby. Some of these optics are also rechargeable. However, if you get physical with your weapon and want another layer of sighting system, then grab the good ‘ol irons. 

BUIS for the Win

At the end of the day, this is another one of those things that call for preference, and of course, purpose.

If your rifle is mainly a range buddy, then optics precision and magnification will be great. But if we’re talking about SHTF, home defense, and other instances where life is involved, I’d say get a BUIS.

Things can get messy during fight or flight situations. And usually, things start acting up when you need them the most – optics included. Having extra sights helps put you at ease. Plus, the tritium and fiber optic options make sure you can still take a bead on the bad guys in low light. 

Even out hunting an iron sight can perform decently at mid-range or shorter.

Back-up iron sights are not perfect, but we don’t need “perfect” in difficult situations. We only need something that works, and iron sights do just that.

So when your modern optic fails, who you gonna call? BUIS!

The Best Back-Up Iron Sights 

Looking for the best BUIS to add to your AR build? From fixed to flip-up to offset sights, we’ve got you covered with the best backup iron sights for your needs.

Magpul MBUS Gen 2

The Magpul MBUS Gen 2 is easily the best backup iron sight for your AR15. Magpul has been a known player in the field and the MBUS is proof of that.

Magpul AR15 MBUS Gen 2 Sights
Magpul AR15 MBUS Gen 2 Sights (from Brownells)

The Magpul back-up sight, or MBUS for short, is a complete set of front and rear sights. The polymer construction gives you a lightweight add-on, adding only 1.2 ounces in total. Some say that BUIS just brings unnecessary weight, so this is Magpul’s answer to that.


This pair boasts durability as it’s made to stand against operational abuse. The rear and front are flip-up sights that quickly spring to action the moment you need them. Just press the sides or top and you’re good to go.

The post front comes with a tool for elevation adjustment to make sure it’s not too high (or low). Adjusting the rear sight is just as easy with its side knob. It has a dual aperture system so you can adjust at different ranges.

For longer distances that need precision, you get the smaller aperture by default. Just flip it down and you’ll get the larger aperture, ideal for closer encounters.

Aside from black, you can also get your MBUS in flat dark earth color option. Attach it to any Picatinny rail, at any distance you want it to, tighten the screw, and it’s all set. This sight locks in place and holds zero like its dear life.

The only thing to remember though is that heat isn’t something polymer is very fond of. With that said, you cannot install the front sight on railed gas blocks or any MOE handguard.

If you’re not convinced by polymer sights, then get the MBUS Pro Sights. These are steel-version irons by Magpul that are as sturdy as they are reliable. It’s an ideal iron for your platform, though, not something for the cheap. 

Verdict

The MBUS has been a crowd favorite for a long time in the BUIS department. I even have some pairs myself and they’ve held up through the years (and counting). At around $80 to $90, this sits in the middle-range of the price spectrum. This is already a great deal since you’ll definitely get more than what you paid for.

Pros
  • Lightweight
  • Easy to install
  • Dual aperture
  • Durable construction
  • Spring-loaded flip-up sight
  • Adjustable front and rear
Cons
  • Cannot be installed on a railed gas block

Bugleman Foldable Fiber Optic Sights

The Bugleman Foldable Fiber Optic Sights is another set of polymer BUIS. It has the weight advantage, plus it comes at a lower price.

Bugleman Foldable Fiber Optic Sights back part with adjustment mechanism
Bugleman Foldable Fiber Optic Sights back part with adjustment mechanism (from Gun Gear Depot)

This is a low-cost fiber-optic sight that glows under the sun. It is no night sight, but the extra glow is something I wouldn’t mind having any day.

The pair comes with an Allen wrench to help with adjustment and installation. They attach to virtually any Picatinny and Weaver rails. To adjust, the front sight has a rotating gear at the back. There’s a knob on the rear sight for windage.

Bugleman Foldable Fiber Optic Sights front and rear aligned
Bugleman Foldable Fiber Optic Sights front and rear aligned (from Gun Gear Depot)

The colors provide instinctive aiming points. It brings an advantage to the table where non-fiber irons can’t. The red glow of the front post makes aligning easy with the green rear. This rear has a dual aperture for CQB and more precise shooting.

These flip-up sights use a thumb-slide mechanism to engage and release for action. Just remember though that this is not for railed gas blocks. The only other thing to also consider is the fitting. You may need to tighten them a bit extra to make sure these sights are in place. 

Verdict

The Bugleman Foldable Fiber Optic Sights is a set of low-priced backup irons. The glow provides a great sight picture. It may need a bit of adjustment in some areas but if you have basic needs, it’s the one for the job. It’s ideal for range guns and, if you’re into some fun, it’s great for airsoft rifles too.

Pros
  • Fiber sights
  • Low-cost
  • Lightweight
  • Comes with an Allen wrench tool
Cons
  • Fitting problems
  • Not for railed gas blocks

Daniel Defense Fixed Sights

If you’re looking for the most durable backup iron sights, then lucky you because you just found it. What’s more, is that it’s made in the USA.

Daniel Defense Fixed Front and Rear Sights Combo
Daniel Defense Fixed Front and Rear Sights Combo (from Brownells)

The Daniel Defense Fixed Sights are made to last. You can be confident that what you have on your rifle is something you can depend your life on. 

This is a fixed front and rear combo that screams toughness and durability. First of all, they’re made of aircraft-grade aluminum. There’s no need to worry about heating problems, unlike polymer sights.

On top of that, they are mil-spec hard coat anodized. That means abrasion and corrosion will be the least of your worries. Installing is just as easy. Plus, you only get an additional 2.8 ounces with both sights on. The rear has a dual aperture and adjusting windage only needs the tip of a spare bullet, which is really handy.

Another thing that makes these irons stand out is their slim and streamlined design. They have concave-like sides which don’t get in the way when using the charging handle. They’re snag-free and are very premium-looking. Well, not just the looks, because these bad boys have a lot to say when put to the test.

Since it’s not foldable, it’s something you can readily co-witness with your red dot. For some, this can mean a busier sight picture. If co-witnessing isn’t for you, then you might want to check the other flip-up sights on this list. 

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Verdict

There’s really nothing to change about these Daniel Defense sights, except for the price. At around $130, you can get more than two polymer BUIS at this price. Still, if that’s cheap polymer we’re talking about, then it’s just like throwing your money away. 

Overall, this is a good investment in the long run. If you pay a premium, expect to receive premium – the flood of five-star reviews will vouch for that. After all, it’s backup irons like these that separate serious shooters from hobbyists.

Pros
  • Lightweight
  • Slim profile
  • Streamline design
  • Dual aperture
  • Holds zero well
  • Aircraft-grade aluminum construction
  • Hard coat anodized
  • Made in the USA
Cons
  • Higher price
  • Busier sight picture

Ozark Armament 45 Degree Offset Sights

If you use a riflescope or magnifier, then the Ozark Armament 45 Degree Offset Sights will be a great backup.

Ozark Armament 45 Degree Offset Sights
Ozark Armament 45 Degree Offset Sights (from Amazon)

As the name implies, these BUIS are not aligned with your rifle. They are offset by 45 degrees, which means you have to tilt your gun when using it. While this is something that might take some getting used to, these aren’t made for the tacticool club. 

This offset sight combo is perfect if your main optic is a riflescope. Unlike red dots, it takes more room in your rail and, most often, doesn’t leave any for other add-ons.

The Ozark Armament sights are a reliable backup that’s always on standby. They’re readily available and allow for a quick transition from your main optic. This is especially useful when you aim from long to short-range shots, and back again.

Ozark Armament 45 Degree Offset Sights

The front sight uses an A2 post that’s adjustable for elevation. What’s great about the rear is that it’s adjustable for both windage and elevation. Like other backup iron sights, it has an aperture for CQB and a finer peephole for precision. 

These sights attach to any Picatinny rail, with hex screws to keep them more secure. Plus, there’s an Allen wrench included for installation. They’re not plastic, so there’s no need to avoid gas blocks – the bane of the existence of polymer sights.  

Since these backup iron sights are offset, they can be prone to snagging. Though that’s nothing to be worried about since it’s made of military-grade aluminum. Once locked to the Picatinny rail, the sights hold like magic which is quite impressive. And for a $35-ish BUIS, that’s saying a lot. 

Verdict

The offset backup iron sights from Ozark Armament is a complete combo that’s always on the go. They’re always deployed and ready for action, all while not getting in the way of your line of sight. 

If you’re looking for offset BUIS that are as affordable as they’re solidly built, then look no further.

Pros
  • Readily deployed backup sights
  • Military-grade construction
  • Sturdy and rugged
  • Dual aperture
  • Quick optics to irons transition
  • Affordable
Cons
  • Prone to snagging
  • Needs some getting used to

Feyachi S27 Fiber Optic Iron Sights

If you’re still on the fence about getting a backup iron sight or not, then let our best-budget entry convince you. Behold the Feyachi S27 Fiber Optic Iron Sights – your best-budget BUIS!

Feyachi S27 Fiber Optic
Feyachi S27 Fiber Optic Iron Sights (from Amazon)

This is a pair of low-profile sights that measure less than half an inch when folded. This is the kind of accessory you can forget about having, but is always ready when your main optic fails. Of course, you can also leave them for co-witness.

They’re not spring-loaded, so manually flip them up when needed. Push the side buttons when it’s time to fold them down. This might not be the most exciting thing about this sight, but it does the job, and that’s what matters.  

To install, use the Allen wrench that’s included in the package. They attach to any mil-spec rail. Adjust the rear’s windage using the side knob. The A2 front post, however, has no tool.

See an unboxing video below:

The red front and the green fiber dots on the rear glow extra when there’s ambient light. This is a nice feature that allows for quicker target acquisition. Also, the rear sight has a precision peephole and a larger one for situational awareness.

What’s really impressive about this sighting is that it is made of quality aluminum. No need to worry about chipping and breaking with this one. For only $29.99 (as of writing), you get a full set with a front and rear sight.

Verdict

This is a decent pair of aluminum sights that cost even less than some polymer sights. The mil-spec finish makes them even more resistant to wear and tear. These sights mean business when deployed – just how we want our BUIS to be.

Pros
  • Fiber Optics
  • Foldable
  • Low profile
  • Aircraft aluminum material
  • Mil-spec hard coat anodizing
  • Dual aperture
  • Allen wrench included
  • Bang for the buck
Cons
  • No spring for the flip-up mechanism

Honorable Mentions

Backup iron sights options are plentiful, so we added some more to the list to widen your options. 

The MaTech Mil-Spec Rear Sight is a no-nonsense backup iron. It might look familiar if you’re in the service, that’s because this is the issued rear sight for M4s. This mil-spec BUIS can take a beating like no other. Whether you use it to co-witness or not, the Matech rear sight has “tough” as its middle name. 

If you want another piece of trusty aluminum BUIS, then the UTG Low Profile Sights should be on your radar. This is a pair of slim and low-profile sights that easily lock in place and are excellent at holding zero. You can never go wrong with this stealthy combo.

The Dagger Defense Tactical Flip-Up Sights are decent BUIS. They’re made rugged by aluminum alloy construction, topped with a matte finish. They are remarkable and lightweight and are always a good addition to your platform. If you want quality and affordable irons while supporting a vet-owned brand, then have at it.

Conclusion

Backup iron sights will always be the go-to sighting system. Optics have revolutionized the way we shoot, but irons make sure we have a last line of defense. As they say, it’s better to have them and not need them than need them and not have them. 

As for the best BUIS, we recommend the Daniel Defense Fixed Sights for solid reliability. The precise and streamlined design makes it the kind of backup that will outlast your rifle’s life. 

In the polymer department, the Magpul MBUS Gen 2 is your best bet.

Now if you want something with a better price tag, then check the Bugleman Foldable Fiber Optic Sights. They’re affordable and, as many have pointed out, they never disappoint.

For more sights-related goodies, you can also check:

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