Optical gunsights are amazing. They make targeting, identifying and engaging distant threats a simple matter of point and click —  or more appropriately, point and bang. Even the U.S. military, who once found the idea of infantry with anything but iron sights abhorrent, now issues optics to nearly every rifleman.

However, those electronic optics aren’t perfect. Batteries die, lenses crack, zeroes are lost and tritium fades. Rather than keep a spare optic on hand, a more practical solution has been running a pair of back-up iron sights (BUIS). Shooters running a carbine or rifle for anything outside of plinking or casual shooting should invest in a quality, reliable set.

Sounds easy, right?

Wrong.

There are dozens of brands in as many variations, and several are only compatible with certain optics, rifle mounts or stock configurations. Like anything else, it’s easy to find the right one when a shooter — or retailer — knows what they’re doing. The best way to zero in on the best BUIS for a rifle is to first identify a shooter’s needs and balance that against what sort of optics they’re using.

A good place to start is the most simplistic. Is a shooter running an optic? If not, they can stop reading now. They don’t need a backup sight since they’re already using the most durable option available.

If a shooter is running an optic, is this sight magnified or not?

Shooters running unmagnified optics have vastly more options for BUIS than those using telescopic sights. Magnified, optical gunsights preclude the use of fixed iron sights because they distort proper sight picture, making alignment impossible.

Depending on the scope’s eye relief, some folding iron sights occupy too much space on the receiver, preventing the shooter from getting close enough for proper use. Mounting height also plays a role; most fixed iron sights are too tall and interfere with mounting magnified optics. This is especially true on the AR-15, which has sights are taller than other rifles due to the system’s inline design.

One ingenious solution to this problem is the Magpul MBUS PRO Offset Sights. Unlike the first Magpul Back Up Sights, dubbed “MBUS,” these are constructed of steel and offset 45 degrees from the barrel. So if a shooter is running an optic with very little eye relief, like an Elcan Spectre, they can mount these diminutive irons closer to the rear of the receiver, allowing the optic to get closer to the user’s face where it belongs. Also, if a shooter needs to employ them, they don’t need to remove the optic, but simply tilt their rifle 45 degrees, pop up the sights and engage.

The only downside to these optics is the one thing that makes them different — their offset placement. While this is a simple, effective solution for short- to medium-range targets, it struggles both at distance and when firing from cover. Achieving correct shoulder placement, cheek weld and sight alignment while bending around cover is difficult enough when holding the rifle properly. It becomes frustratingly difficult when the rifle must be canted while leaning. Though in all fairness, this is a true backup sight, not a battle sight that doubles as a backup.

Going 1X

Shooters running unmagnified optics have it easier. Their options are only limited by optic height. If the irons align through the optic, they’re good to go.

This is known as co-witnessing. There are several different ways to do this, but the basic premise is to align iron sights through an unmagnified optic, thus allowing shooters to use the same hold, cheek weld and shooting position to engage targets.

There are two main ways to co-witness iron sights with an optic — partial and full. Full co-witnessed sights are those that align in the center of the optics window. Partial describes those that are only partially visible through the optic.

These are further broken down by where they are visible through the optic, either in the lower third of the sight picture or the upper third. Lower third has the benefit of increased field of view while aiming at the cost of having the iron partially obscured. Upper is the opposite, making the sights easier to see, while obscuring more of the target.

One of the most streamlined configurations for this setup is to simply use either the original carry handle or a removable-handle sight and front sight tower with a co-witnessed optic in between. This doesn’t change the rifle’s profile, but provides an immediate “always on” option should a shooter’s optic fail.

The downsides of this configuration aren’t insubstantial. For starters, the carry handle rear sight is very heavy and big. Because of this, it blocks the majority of a shooter’s forward field of view when aiming down their sights.

Lastly, the carry handle uses all the available rail space on the receiver. This means any optic mounted forward of it must be attached to a railed handguard, which raises additional concerns. The rifle then needs a rail installed that holds zero enough for an optic. Once the optic is mounted, the rifle becomes nose heavy, making it difficult to hold on target for extended periods.

A better option that retains all the benefits with far fewer downsides is a folding rear sight. Like the carry handle option, the folding iron sights permit co-witnessing and are perfectly suited to unmagnified optics like AimPoint reflex sights or EOtech holosights.

The largest benefit of a folding sight over a fixed one is the increased situational awareness it gives a shooter.

Unlike the fixed variety that are always in a shooter’s field of vision, folding sights fold out of the way. They are far smaller than carry-handle sights, freeing up receiver rail space. Optics can then be mounted closer to the receiver, better balancing the rifle. This also means shooters don’t need to invest in a railed handguard, saving weight and money.

These, too, require some special considerations. If a shooter decides to buy what the U.S. military commonly issues, the MaTech BUIS, they should be aware of its shortcomings. While the MaTech is overbuilt with quality hardened steel, its reliance on spring pressure to hold zero makes it a poor choice for serious work. But the MaTech does have some desirable features, such as the easily adjustable range settings out to 600 yards and its ultra-low profile when folded away.

A more versatile choice is the GG&G MAD Flip-Up BUIS. Just like the MaTech, the MAD sight folds down when not in use and features adjustable range settings with easy-to-read white markings. Unlike the MaTech, the MAD uses a locking detent to hold it upright when deployed and has two aperture settings. One is smaller, allowing for fine aiming at distance. The larger aperture permits faster target acquisition and engagement at close range. Both are designed for use with “F-marked” front sight towers. Most quality rifles use these, as they’re made for use with flat-top receivers, so this isn’t normally an issue.

Another type of backup sight rarely mentioned is built-in backups. While their usefulness is dubious at best, they offer some peace of mind to shooters concerned with an optic’s longevity. Rarely found on civilian or hunting optics, high-end combat optics like the Trijicon ACOG and Elcan Spectre series of scopes feature built-in iron sights for emergency use.

The Trijicon uses simple post- and notch-style irons, while the Elcan opts for M-16-style staple aperture sights. On the down side, these sights are sometimes too far from a shooter’s eye to be useful and the sight distance is too brief for any serious work or precision. Still, it beats point shooting — but not by much.

Going Angled

Another option that isn’t a true BUIS is an off-center reflex sight. When mounted far forward, these reflex sights are very usable — they give shooters a huge, obstruction-free field of vision, ideal for tracking targets. Competitive shooters also enjoy these as a close-range alternative to their low-magnification optics. For the sake of keeping the rifle light and maneuverable, the ideal optic for this is a micro red-dot sight.

Since this optic is primarily for emergency use, it’s important that it functions when needed. Shooters looking for a suitable optic should opt for a lightweight, low-profile (less likely to snag and break) option with excellent battery life.

An excellent choice for a backup optic that won’t break the bank is the economical Hi-Lux Micro-Max B-Dot. The B-Dot utilizes the same mounting system as the Aimpoint Micro — giving it access to dozens of mounting accessories and methods. Shooters who invest in one can do so without much risk — if they don’t like using it as a backup sight, a few bucks more can purchase a standard or raised mount, allowing shooters to run it as a dedicated short-range optic if they want.

It runs on a single CR2032 battery and manages to stretch it for an average of 55,000 runtime hours. With a dozen brightness settings, night-vision compatibility, half-MOA adjustability and included killflash cover, the Micro-Max offers tremendous value to buyers.

Stock Them All

Backup sights of any variety simply act as an extra level insurance that a rifle can still be effectively used. Just like backup guns, knives, even spare magazines, these demonstrate how risk-aversive gun owners are, which makes the contentious nature of backup iron sights so atypical of the culture.

Some contend backup sights are superfluous in an age where optics are nearly as reliable as fixed sights. My perspective is why take chances? For the cost of a few boxes of ammo and a few ounces of added weight, shooters have an extra level of security to ensure their carbine stays combat effective.

Soldiers, law enforcement and competitors alike are well aware of Murphy’s Law. Optics fail, batteries die, zeroes are lost — all manner of minor catastrophes can take a shooter out of the fight in an instant, the consequences of which range from a disappointingly long stage time to a tragic death with an otherwise fully operational firearm.

Backup iron sights normally aren’t needed, but isn’t that the point? They’re utilized when a primary aiming device fails. Concealed carriers don’t use their chosen handguns every day in defense of their lives, just like seatbelts won’t save your life every day, either. Does that mean you shouldn’t carry your gun every day and not buckle up? No. Of course not.

As the most prepared demographic in the U.S., gun customers understand firearms aren’t magic, they’re mechanical. Unforeseen events happen. Shooters of every variety actively plan to clear malfunctions for the same reason they use backup sights. Because of this, the mantra “fail to plan; plan to fail” is central to gun owners.