The Top 5 AR 15 Back Up Iron Sights 

Back-up iron sights are an interesting discussion. They rarely get highlighted in the spotlight of the modern rifle sights. They just sit on the rifle and are likely never used because of just how great optics are and how comfortable the average American’s rifle remains. We aren’t scaling cliffs in the ‘Stan fighting the Taliban so our optics tend to last as long as our rifles. This doesn’t mean we shouldn’t have or discuss back up iron sights. 

Heck, it doesn’t mean we shouldn’t be training with these sights, either, ensuring they’re zeroed and ready. I doubt most of us give irons much time since optics rule so hard. Recently, I’ve been working with iron sights and BUIS (back up iron sights), giving them more time at the range, more time for dry fire, and also researching my options. I’ve had some hands-on time with a few sets of BUIS and I want to provide you with what I think are the top five backup iron sights. 

Why back up iron sights?

In case your optic breaks — that’s the most obvious answer! You still need a sighting system to aim your weapon and BUIS are the easiest option. They are relatively affordable, take up very little room, fold out of the way, and weigh nothing. If your optic breaks, pop them up and keep going! 

It’s like a life jacket or a fire extinguisher. You likely won’t need it, but it’s nice to have when you do. Also, as I’ve discovered recently, shooting with iron sights can be a lot of fun. I’ll use my optics for real shooting, but iron sights can be a ton of fun at the range. It’s a little more challenging, but also more rewarding. To me, shooting and training are fun. Mixing in iron sights increases my enjoyment of the activity. 

So what are the best backup iron sights on the market? 

5. MBUS Standard 

If you are on a tight budget the Magpul MBUS standard sights are fantastic. They are made entirely from polymer, but it’s not your dad’s crap-plastic. Magpul has mastered the art of polymer and MBUS sights are a great set of sights on a budget. The MBUS standard sights are flip-up iron sights that drop onto your AR-15s rail and receiver with ease. 

Magpul MBUS back up sights
The MBUS Sights are plastic fantastic.

MBUS stands for Magpul Backup Sights and these have become a go-to standard for some years now. The front sight features a semi hooded front post that adjusts with ease. The rear sight features both a close range and precision-oriented aperture. One is wide open for quick sight acquisition and the other is fairly tight for accurate long-range shots. 

Sure they are polymer, but they are likely to remain folded and out of the way so it’s not like they’d face a ton of abuse. 

4. Magpul MBUS Pro Sights 

Yep, another Magpul set of sights. The Magpul Backup Sights Pro differs in its construction from the standard. Gone is the polymer, as the Pro sights are all-metal sights. The use of metal does a few things. The sights are more durable and they have an even lower profile. Yes, they are considerably more expensive, but if you want metal you have to pay for it. 

Magpul MBUS Pro back up sights
If you don’t trust plastic Magpul has you covered with a set of all-metal sights.

These all-steel sights are treated with a Melonite QPQ finish and case hardened to protect them from corrosion. They lock in place with positive detents in both up and down positions so they stay exactly where you want them. My favorite feature of these sights is the tool-less adjustment. Textured elevation and windage dials make it fairly easy to get your irons on target and to even make adjustments if you are taking some seriously long shots. 

The front sight is designed with the use of laser aiming tools in mind and is thin enough to prevent blocking your beam. The MBUS Pro Sights might not be cheap, but they are very well made and thought out. 

3. XS Flip-Up Sights 

XS Sights is mainly known for its massive handgun sights designed for close-range, defensive shooting. Believe it or not, they’ve teamed up with Sampson and CSAT to produce a very robust set of backup iron sights. They aren’t small, and they are heavier than others, but they are very versatile. The Sampson bodies are tough and dependable, and allow the sights to be easily folded out of the way. 

XS Sights flip up back up iron sights
The XS Sights are big but versatile.

The rear aperture is the CSAT design. It’s a three aperture system. We get our two peep sights for close-range speed and long-range precision which is pretty standard. We also get a set of open sights much like a handgun that sits above the precision aperture. This allows for an instant transition from precision to CQB. The front sight is where XS comes in. It’s big, white, ey catching, and features a tritium lamp that glows in the dark. 

The XS flip-up backup iron sights are quite pricey but they are a very versatile iron sight option. 

2. Knights Armament Company Folding Micro Sights 

Do you know why I love the KAC Folding Micro Sights? Well, besides the free lanyard they give away at SHOT, this is the thing Knights makes that I can afford! Seriously, the micro folding sights are outstanding. They are used by the Army and Marine Corps and have been proven to be extremely reliable in the worst situations. 

Knights Armament Company folding micro sights
KAC is the most trusted option by the United States Military.

The rear sight is designed for engagement out to 300 meters with an adjustable windage rail for on-the-fly corrections and easy zeroing. The Micro Front Sight is a small, low-profile design that works well with lasers and stays out of the way. The front sight post can be easily adjustable via an elevation wheel. When folded both of these sights form the smallest backup iron sight footprint on the market. 

KAC folding micro sight
KAC is the most trusted option by the United States Military.

If you want what our soldiers and Marines use this is the way to go. 

1. Ultradyne C4 Sights 

Innovation isn’t dead in the world of iron sights and Ultradyne has proven that. The C4 sights are my absolute favorite backup iron sights. They do a lot of things right, but what stands out the most is the front sight post. It’s not solid—a 12 MOA hole sits in the front of it. You look through the rear sight to see the front sight which you also look through to see the target. The front post can be swapped from an 8, 10, or 14 MOA post as well. 

Ultradyne C4 back up iron sights
Even iron sights can be innovative.

This design allows you to see the target and focus on the target, almost like a red dot, making it easier to hit targets at longer ranges with your iron sights. The C4 sights are all metal, they fold, and they’re super modern. You can adjust the sights without tools, deploy them with a single hand, and you can swap the rear aperture to tighten it down or loosen it up. 

These sights have to be used to be fully experienced. Give them a try if you want the best backup iron sights out there. 

Sighting In 

Backup iron sights aren’t easy to use compared to a red dot or LPVO, but they are rewarding. They can also be super valuable to have when things go south. A good set of backup iron sights can be a lifesaver. Sadly, there are lots of Wish rade iron sights floating around out there. Hopefully, I’ve helped you find a good set of backup iron sights, and maybe I’ve inspired you to train a little with them. 

Travis Pike is a former Marine Machine Gunner and a lifelong firearms enthusiast. Now that his days of working a 240B like Charlie Parker on the sax are over he's a regular guy who likes to shoot, write, and find ways to combine the two. He holds an NRA certification as a Basic Pistol Instructor and is probably most likely the world's Okayest firearm instructor. He is a simplicisist when it comes to talking about himself in the 3rd person and a self-professed tactical hipster. Hit him up on Instagram, @travis.l.pike, with story ideas.

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