The AR-15 family of rifles is one of the most prolific and effective in the world. In the guise of the M16 rifle or M4 carbine it has served continuously as the U.S. armed forces issued rifle for over 50 years, and has been adopted by dozens upon dozens of other militaries around the world.
It is also widely employed as a patrol rifle by police and government agencies, to say nothing of the more than 15 million AR-15 variants that have been commercially produced in the U.S.
Any system is only as reliable as its weakest component, and a common weakness for a firearm is an inferior magazine. Rifles, including the AR, are no different. The AR has seen many improvements and innovations over the course of its long life, among them many revisions to the design of the magazine.
Accompanying the dizzying array of other components and accessories available to a user today, there are over a dozen different types of magazine: constructed of original aluminum, steel or polymer, and each has many unique designs.
Each varies in its reliability and usefulness, some being supremely reliable and others only of marginal effectiveness.
In this article, I will detail a compressed evolution of the AR-15’s magazine, from its inception to today, discuss what makes a quality magazine, and offer my opinion of what the best “standard” magazine is today. Read on, and let’s begin.
Evolution of the AR-15 Magazine
The AR-15 is descended from Armalite’s earlier AR-10, itself a “Space Age” rifle of the day, that used a suitably advanced magazine: one made of lightweight aluminum, pressed with a grid or waffle pattern for rigidity and intended to be so cheap and available as to be disposable. Aluminum has many material advantages, such as very light weight, very good corrosion resistance and good strength when alloyed properly.
The Vietnam War-era M16A1 rifle used similar magazines to the AR-10: lightweight, 20 round magazines, these with made with long grooves instead of the AR-10 magazine’s waffle pattern, and intended to be disposable.
Later on, around 1970 30-round versions of this aluminum mag started appearing in the hands of soldiers and marines, and were later adopted as standard issue.
Over the years, various improvements to the standard U.S. Government Issue (USGI) aluminum magazine were implemented, predominately changes to follower design and the magazine spring.
These incremental changes were usually identifiable by the color of the follower, beginning with black, then green and finally tan. In 2016, the U.S. Army introduced the first “major” adopted improvement of the aluminum 30-round magazine, the “EPM”, or Enhanced Performance Magazine.
The EPM uses a new, modified body colored tan so as to not be confused with older, incompatible magazines and redesigned feed lips to, purportedly, increase reliability over previous iterations by 300%.
The U.S. Marine Corps has gone in a different direction and in December of 2016 authorized the issue of the Magpul PMAG M3 for all in service rifles, including the M27 Infantry Automatic Rifle.
The PMAG, long a sort of domestic industry standard in the U.S., and now, after grueling government testing, and service with the British military, it is finally being adopted at home.
AR-15 / M-16 Aluminum Magazine Characteristics
The standard USGI aluminum magazines are most commonly seen in 30rd versions, with modern 20-rounders still being popular with some. The two are easily told apart by the 20rd versions short, straight appearance while the 30rd version is longer with a slight curve or crook in the body.
The finish can be any color from black to a dark or light gray, not including any magazines finished with homebrew camo paint or any other aftermarket finish.
Any rifle is only as good as its magazine, and while much improved today early AR magazines were delicate, especially compared to any of its contemporaries like the AK-47, M14, FAL or G3. Even other rifles’ alloy magazines had noticeably overbuilt feed lips and rugged bodies.
The AR-15/M16 magazines had a reputation for the followers binding in the magazine, causing a stoppage in the rifle at best, or sometimes seriously upsetting the stack of cartridges. This did nothing to help the poor reputation of the Vietnam-era M16, alongside other errors and mistakes during early adoption and rollout.
Malfunctions of that sort were the reason for the incremental follower redesigns mentioned above, and were aimed at creating a smoothly feeding, consistent geometry follower that would be immune to the issues of the past versions.
The latest version, the Army EPM, was tested and supposedly found to offer a huge increase in performance over predecessors. It remains to be seen if this is the case across a large sample size of issued magazines.
Nevertheless, these improvements did undoubtedly help improve overall reliability somewhat, but did nothing to help the other weakness of the aluminum magazines design: the fragility of the feed lips to being bent out of spec.
The Achilles’ Heel of Aluminum Magazines
Correct feed lip geometry is critical to a properly functioning magazine. The feed lips hold the next cartridge for loading in the proper orientation to ensure it is picked up by the bolt at the right angle for its short journey up the feed ramps and into the chamber. If this geometry is changed, either from damage or fatigue, malfunctions will start to occur.
If you examine the feed lips of the current and legacy aluminum magazines, you will see how obviously delicate they are. A magazine used in battle or training must endure considerable rough handling, be it from dropping, a sharp impact from a botched reload or merely wear and tear from being loaded off stripper clips and their guides.
The Devil is in the details, and it does not take much deformation of the feed lips to start inducing malfunctions, and what little does need to occur is very difficult to detect.
A special gauge can be used to quickly ascertain if the feed lips are serviceable, but these gauges are not issued to troops, and furthermore never seem to be around when needed.
The most insidious problem with the alloy magazine is the fact that those same feed-lips, when a magazine is found to be defective or just not working properly, are easily “tweaked” by the well-meaning user, and this sometimes is enough to return the magazine to acceptable levels of performance.
The offending feed-lips, though, have been seriously weakened, undetectably, first by the initial damage and then the corrective measure, so that they will be much more prone to deformation in the future! So if the magazine is turned back in to the arms room, or put back into the “duty” rotation, it is now a matter of time, waiting to malfunction again.
Some companies, most notably H&K, turned to designing a “high-reliability” steel magazine to address these shortcomings. Regrettably, while somewhat more durable, the feed lips remained vulnerable to deformation as described above. Thanks to this persistent weakness and their very high cost (upwards of $50 per magazine!) they never caught on in great numbers.
Polymer to the Rescue
Polymer magazines are not new, having been around in one guise or another since at least the 80’s. Early polymer AR pattern magazines were the Orlite and Thermold varieties. Neither worked very well, being comparatively delicate compared to metal magazines, often not as reliable and with the additional weakness of being vulnerable to melting.
Polymer AR magazines remained an “also ran” product until Magpul, a company previously known for a simple, handy rubber loop designed to extract AR mags from pouches, released the now ubiquitous PMAG in 2007. The rest is history.
The PMAG was the first polymer magazine to combine excellent feeding reliability with superb ruggedness and durability. They were inexpensive, easier to disassemble for cleaning or maintenance, and included other features like an stowable top cover designed to both seal the magazine and alleviate pressure on the feed lips when stored loaded.
After a series of well publicized demos and very good marketing, they caught on like nobody’s business, spawning a number of imitators and competing polymer magazines.
After a couple of generation upgrades that slightly improved material construction and feed geometry, today the Gen 3 PMAG is the de facto standard for the AR-15 and M16 family of rifles, being completely superior to the older aluminum magazines in almost every way.
A major benefit of the PMAG and other quality polymer magazines is that the feed lips are more rugged than aluminum designs. In addition to this perk, if the feed lips are ever stressed beyond a point that they are able to bear without failing, they will visibly break, making inspection of magazines for defects much simpler.
PMAGs do have a few quirks, such as a reputation for not falling free in some patterns of AR’s, or non-AR weapons that utilize the AR magazine, like the SCAR. Magpul addressed this issue earlier by introducing the EMAG; essentially a PMAG with modified a modified body designed to fit other rifles more easily or without modification, especially foreign ones.
Other major manufacturers’ polymer magazines incorporate a different features or a different design ethic: One excellent competitor, TangoDown’s ARC magazines utilize a consistent-feed internal geometry, and are designed to fall free from any AR. They are a very reliable and viable option, and have earned a good reputation.
Some other companies have polymer magazines with steel feed lip inserts, nifty-looking hexagon patterns in the bodies or various other gimmicks. Some work well enough or are merely average, and others are of decidedly lesser quality.
Considerations for Using Modern vs. Legacy Magazines
While modern polymer magazines are the performance standard, this does not mean that alloy magazines are unsatisfactory. I believe the advantages of polymer are undeniable in all but the most remote circumstances, having been proven in over a decade of relentless testing and operation in every climate on earth.
Modern polymer magazines also typically allow you to load a full 30 rounds and still seat the mag on a closed bolt, whereas many fully loaded alloy magazines will be very difficult or impossible to seat on a closed bolt, leading to some users downloading by a couple rounds. All that being said, some users may have operational requirements that mandate metal magazines, or simply prefer them to polymer.
This can complicate employment somewhat because there are a great many makers of alloy AR magazines compared to polymer ones and many of them are of inferior quality. Additionally, the supply of older “surplus” magazines still in supply means many users of alloy mags have a mish-mash from different eras and generations of improvement. Sorting the wheat from the chaff can be challenging.
In such instances, my recommendations are simple: When buying or replacing magazines, buy good magazines from known-quality makers and you’ll likely have no issues. Known makers of good magazines are Bravo Company Manufacturing and Okay Industries, with Okay Industries making probably the finest alloy magazine widely available.
When a malfunction is traced to a magazine, notate it. If a magazine of any make induces a malfunction twice, retire it permanently and unceremoniously via destroying it and then trashing it. Do not let someone come along and retrieve it, possibly endangering their life.
If you have an older magazine that you use regularly and it gives you no trouble, march on. Age alone is no reason to discard a good piece of equipment. However, don’t get sentimental about your magazines!
While not truly disposable as was originally intended with the AR-10 and AR-15, they are consumable items that will wear out even if babied. When they stop functioning at 100% discard them and buy new ones. At the very least, if you must keep it, distinctly mark it so that it will only be used for practice and training, nothing else.
As far as I am concerned about the plethora of polymer magazines today, the only two I buy that I depend on and have worked 100% of the time with no issues are Magpul PMAG’s and TangoDown ARC mags. It has been my experience that others either offer no performance increase for their greater cost, or are deficient in areas of durability or reliability.
If you want to try other brands for evaluation, fine, but you will have to try a great many of them over a long time to even get close to the amount of assurance you would have if you just bought a PMAG or ARC mag instead.
Whatever magazines you select, performance speaks. It is an essential component for proper functioning of your rifle, and so long as it works 100% of the time and does not have to be hammered in or out of the rifle, do not get too caught up in trying to find the “perfect” magazine.
Storing of Magazines
When storing magazines, the same basic rules apply as when storing firearms: avoid damp locations, and use desiccant or dehumidifiers to reduce moisture in the storage container. AR magazines can be stored loaded with a few caveats.
Use caution when leaving alloy magazines stored loaded for long periods of time. The pressure of the fully compressed spring pressing the cartridge stack against the feed lips can lead to the lips spreading apart, changing their geometry and causing the malfunctions discussed above.
Note that leaving a spring compressed for a long time (in the case of modern magazine springs) does not cause it to lose its strength as is often asserted, or at least very, very little strength, assuming that it is not stored in excessively high temperatures.
If storing a PMAG loaded and worrying over feed lip deformation, which has been tested extensively in the above example, you can simply use the snap-on top cover which will alleviate the pressure on the feed lips.
The AR-15 design has been around awhile, decades now, and has seen many revisions and versions of its magazine come and go. From classic alloy to the most modern polymer, the only thing that matters about the magazines you choose is that they are durable and function reliably.
Whatever your preference, buy them cheap, stack them deep and decommission any troublemakers and you’ll find that any of them are up to the job of keeping your rifle firing for a long time to come. This goes without saying, but you should also get your firearm from a reputable dealer; obviously you can find the perfect AR 15 rifle for sale online.
What is your preferred material for magazines, polymer or metal? Have you found one brand to be superior to all others? Let us know in the comments!
Chad Nabors specializes in firearms, with a strong focus on concealed carry and pistols. His background is in commercial sales and training, and armor development and testing. He has trained many citizens on the pistol from basic to advanced skills. He is a vociferous proponent of the 2nd Amendment, and believes that defense of self and family is a moral obligation. He can be reached at grimgunner (AT) gmail.com.