The Best .300 Blackout Magazines
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The .300 Blackout is one of the more interesting calibers in recent years, officially approved by SAAMI in 2011, and born out of a need for a specialized close-combat round for special operations units, the .300 AAC Blackout has become one of the most popular chamberings for the AR-15 platform – and for a good reason.
Offering better ballistic performance and stopping power than the standard 9mm (the most popular subsonic SMG round) in subsonic AR setups, and you can run standard 5.56 magazines with any rifle chambered in .300 Blackout as the case dimensions are close enough to function in both.
In This Article
.300 Blackout Magazine Comparison
Below is my list of the best .300 BLK magazines for 2022. I list the best choices in terms of value, performance, design, and cost.
Click on the name to head to the product page, read reviews and check prices or skip ahead to the list of magazines.
Best 20-Round Mag
.300 Blackout Magazine Picks
1. Magpul PMAG 30B GEN M3
The Magpul GEN M3 is a go-to magazine in any caliber and their .300 BLK mag is no different. Like its smaller-calibered brethren, the .300 BLK Pmag line retains all of the great Magpul GEN M3 features – like their crush-resistant polymer & aggressive front and rear texture.
The PMAG 30 AR 300 is impact and crush resistant, plus the anti-slip and anti-tilt tech make them some of the most durable and best-designed magazines for rifles available.
These Gen M3 PMAGs mitigate cross-loading by adding .300 BLK-specific next-generation features — like distinct rib design, rear texturing on the magazine body, and an easily-removable, slim floor plate, and stainless steel spring.
Additionally, they also have the GEN M3 paint pen dot matrix, so you can denote .300 Blackout on the magazine itself, which is an imperative when using a common magazine for multiple calibers.
2. D&H AR-15 20 Round 300 AAC Blackout Magazine
Instead of opting for an aggressive front texture or specific ribbing, D&H keeps cross-loading at bay with a simple approach: include a visual indicator of the caliber on the magazine from the factory.
These magazines from D&H offer a 20-round capacity and a bright red follower paired with a specially-calibrated spring which improves follower/spring tracking and feeds the heavy .300 Blackout rounds more effectively than a standard 5.56mm magazine.
They’re made out of high-quality, black anodized aluminum for years of service and a solid lock into any AR mag well. The inclusion of the caliber on the magazine from the factory is nice and certainly looks more consistent than a DIY job with a paint pen.
One thing to keep in mind with aluminum magazines, they’re durable but can bend and dent rather than break (like polymer magazines might). With that said, it’s always a good idea to inspect the feed lips on aluminum mags occasionally to ensure they’re still in shape, especially after considerable use or they’ve been dropped.
3. Hexmag HX40 Series 2
Most AR owners have a lot of black Pmags laying around — it’s not uncommon to have a dozen or more at hand. Grabbing another Pmag and painting it for .300 Blackout might not be the best choice.
Many shooters will dedicate specific types or brands of magazines to specific calibers. Breaking calibers out this way further prevents mix-ups and improves safety by making it easy to pair a specific caliber with the correct magazine.
Right in the same budget ballpark as the Pmag, these Hexmags have a hexagonal texture on the whole magazine, a red follower, and a matching red button on the bottom to view the floor plate.
These simple touches make you less likely to misidentify the magazine, making these more than worth looking into. Using different mags for each caliber (like Hexmags for .300 BLK and Pmags for 5.56mm) will prevent cross-loading and simplify your range day packing.
4. Magpul Pmag 20 Round M3
Another way to avoid cross-loading — again keeping the feel of the magazine in mind — is to change its shape, and this 20-rounder from Magpul has a shorter length than the 30 rounder, making it easy to distinguish.
The 20 rounder offers the same great Pmag features but measures in at a few inches shorter — so it’s smaller in-hand. Add some visual indicators like a specific caliber in the DOT matrix, and this gives you a great solution without breaking from Magpul products if they’re your thing.
5. Magpul M3 Windowed Pmag
Keeping with the theme of changing things visually, many shooters use windowed Pmags for specific calibers like the .300 Blackout. We all have black magazines lying around, so changing both the color and adding a clear window to inspect the remaining rounds will help avoid confusion and give you an even more useful magazine for .300 BLK rounds.
One potential downside is these are traditional 5.56mm Pmags (which include the “5.56×45” notation) so if you’re not going to use the color of the magazine itself and a differentiator it’s would be a good idea to use a paint pen to clearly demarcate the intended caliber.
Again, the idea is to give yourself as many visual and tactile indicators of the intended caliber on the magazine, and we think these do a very good job at that. The window in this lightweight polymer magazine is also handy for keeping track of remaining ammunition.
What to Look for in a .300 BLK Mag
1. Identifiable differences
While running a standard magazine is convenient (one of the central features of the .300 BLK is you don’t have to change anything on your 5.56 AR beyond the barrel), there’s additional safety in dedicated magazines, which help mitigate dangerous cross-loading issues (chambering and firing the wrong ammo, causing a catastrophic out of battery detonation).
To keep things as safe as possible, we recommend dedicated 300 Blackout magazines and magazines that offer unique color, distinct follower, or identifiers to ensure it’s clear which magazine houses 5.56 and which contains .300 BLK.
Having magazines for rifles chambered in .300 Blackout will mitigate cross-loading, provide additional safety measures, and give you another reason to add to your kit. What’s not to like?
2. Brand names
Additionally, some of our favorite manufacturers have crafted dedicated .300 BLK magazines.
While these mags are, in many ways, identical to those 5.56mm variants, our recommendations will make it easier to tell them apart in your range bag, give you a sense of the best brands and features – all while keeping price point in mind. No need to head to the bargain bin for your BLK.
Can't I just use a 5.56 NATO mag?
For most gun enthusiasts, most of the time, there’s no functional issue with using a 5.56 NATO mag when loading .300BLK. There is, however, a significant advantage to using a magazine that’s made for a specific caliber.
Differentiation is a must
First and foremost, it’s a good idea to get a magazine designed for the .300 Blackout to prevent you from trying to feed 5.56mm into the wrong rifle, or the other way around — which would lead to catastrophic results.
While this would be a minor inconvenience at the range, it could well be the difference between staying in the fight and a catastrophic failure if you grab the wrong black polymer magazine in the awful event of a home defense scenario.
Using different magazines for each rifle chambered in a specific caliber is an affordable piece of insurance against that kind of preventable mistake and offers a decidedly cheap way to enable diligent ammunition management — ensuring rifles chambered in .300BLK are fed the right ammo.
You can generally use .300 BLK rounds in a 5.56mm magazine without issue, but commingling different cartridges in common magazines is just asking for pain.
A dedicated .300 Blackout magazine gives you a chance to load your BLK in a specific magazine, which can offer a tactile difference or enable you to paint a bright color or use another visual indicator (such as a paint pen on the Magpul Gen M3 or different colored follower) giving you distinct visual and tactile indications as to which magazine is which.
Avoiding (Potential) Feeding Issues
Are we going to tell you that using .300 Blackout rounds in a standard 5.56 magazine is sowing future problems or going to create a feeding issue down the road? No.
Are we proponents of using the right tool for the job whenever possible? Absolutely.
Most polymer magazines — 5.56/.223 magazine in this case — use an internal shoulder rib that is designed to meet the .223/5.56 NATO cartridge at the shoulder, which aligns the rounds and prevents bullet tips from scraping against the inside of the magazine body, giving the user trouble-free feeding.
This rib can tip the fatter .300BLK rounds (generally subsonic ammo in the 115-grain territory) toward the center of the magazine, creating misalignment and potential “bullet pinching” with picky rifles — leading to a slower load. It’s a thing.
.300 Blackout mags are indeed different. They use a .300BLK-specific internal geometry and shoulder rib that enables the rounds to stack properly and prevents feeding issues with the shorter, stubbier rounds – -giving you a more reliable magazine.
Plus, magazines are cheap.
There’s no reason not to have a purpose-designed magazine for your Blackout setup. .300 Blackout magazines often have slightly different followers and geometry to allow for smoother feeding of the larger caliber rounds and projectile weights than 5.56mm magazines, helping to avoid feeding issues.
While the latter can certainly be used in most cases, most of the time, some people have had slight feeding issues with 5.56mm magazines feeding .300 Blackout from magazines that have a high round count.
Considering that .300 Blackout has been on the market for some time now, it’s a logical step to take advantage of small, but important, performance gained from .300 Blackout magazine technology advancements over the last several years. Any gain in reliability is worth looking into from our perspective.
But what about problems with capacity?
If I had a dollar for every time I read someone claim that using a 5.56 NATO mag to load .300BLK would reduce the available capacity below the rounds intended, I would have a few more ham sandwiches each week.
The idea is silly on its face — .300BLK and 5.56 NATO cartridges have the exact same rim diameter — 9.60 mm (0.378 in) — so there’s simply no additional material that would impact capacity.
In fact, while the bullet is larger, the .300BLK round is shorter than the 5.56 NATO — meaning there’s actually more room in a 5.56 magazine when loading .300BLK, which can lead to the above misalignment of the .300BLK when riding a 5.56 mag rib.
I have, on multiple occasions and with various mag brands using windowed magazines and plain jane sticks, successfully loaded a 5.56 magazine to capacity with .300BLK rounds. Anyone who says you’ll negatively impact magazine capacity when loading .300BLK in a 5.56 stick has never actually tried to do it.
Important .300 Blackout Mag Features
- Price. If I’m being honest, the first thing that I look for when buying magazines is the price. Since most magazines are made reasonably well, they’ll function for the majority of shooters for a long time to come. I would rather spend our money on ammunition, so it makes sense to grab the most affordable magazines that you can find. Of course, looking at reviews is vitally important here: frugal is one thing, but cheap is another. Magazines can stop a gun from functioning at the worst of times, so always make sure to buy quality magazines. In short, we’re always looking for deals on magazines so we can spend more on things like ammo and guns.
- Magazine Material. Modern magazines all tend to use some kind of polymer, but there are both metal options available and a variety of polymers used in .300 BLK mags. For instance, Magpul touts the fact their mags are crushproof, while Lancer uses a translucent, hybrid polymer/steel design that provides a visual indication of rounds on tap, but may be less durable than the Magpul approach.
- Feed Lips. Feed lips are the last mile of the magazine — they’re where the round is handed off to the bolt carrier in the chamber, which is a volatile environment. Magpul uses polymer feed lips, and are incredibly proven performers in any environment, but if you prefer steel feed lips you’ll want to look for Lancers or other brands that don’t put polymer in their lips, which can be a matter of both preference and overall reliability.
- Organization. As I’ve said a few times, even though you can use a 5.56mm magazine for .300 Blackout, it’s important not to get the two mixed up when it comes to putting them in the gun. I recommend getting magazines that have some kind of built-in marking system, such as paint dots or swappable plates with different colors. That way, you can tell your magazines apart without resorting to using a permanent marker or spray paint, which we are also not above doing in the least.
Types of .300 Blackout Magazines
Real talk time, kids: most AR magazines, regardless of caliber, are relatively similar — it’s the subtle differences that truly distinguish them from one another. A standard .300 Blackout magazine, for example, might consist of little more than a polymer mag with the correct internal geometry for the Blackout while a more Gucci mag (is that a thing?) might offer windows or translucent sides, steel feed lips, or simply more capacity.
What’s most important about a good .300 Blackout magazine is that it works well with your build and enables you to switch between common AR rounds safely and effectively. That said, in general, there are two types of magazines in .300 Blackout, metal, and polymer.
- Metal magazines are often the most durable and can stand up to a lot more abuse than polymer magazines without breaking. This comes with some caveats, however: no magazine will last forever, and even the toughest magazines will need their springs and followers replaced from time to time to keep them running well for long periods of time. The big bonus here is that the feed lips are integral to the magazine, and are a little more durable than those on polymer magazines.
- Polymer magazines are a little bit lighter than their metal counterparts, but often not by much since the polymer is a fairly sturdy material as well. Polymer magazines tend to work well and have become the industry standard for most people, whether civilian, law enforcement, or military. One weak point in polymer magazines is the feed lips: the polymer feed lips do crack over time and are often the eventual failure point of polymer magazines. Some brands have fixed this by adding metal feed lips, but these can become detached as well.
As a side note, it is also possible to make use of standard 5.56mm magazines, whether metal or polymer, for .300 Blackout.
These will get the job done and feed generally well but will do so at the cost of reduced capacity, usually, 30 .300 blackout rounds instead of 30 5.56mm rounds. I think that this tradeoff can be acceptable, but since magazines are relatively affordable to begin with, it makes more sense to go for magazines that are intended to work with the caliber that I plan to shoot the most, even if something else will get the job done.
Generally, the best option is to opt for polymer magazines that have been designed specifically for .300 Blackout ammunition. In addition to avoiding making a mistake and putting the wrong bullets in the wrong firearm, I like the idea of a company spending a little more time and effort ensuring that our magazines will be reliable over time.
While metal might be a little more durable than polymer, I tend to prefer the latter to save a little bit on weight. Also, polymer magazines are much more widely available and seem to go on sale more often.
.300 Blackout Magazine Pricing
Most magazines are cheap and plentiful, and the same is true with .300 Blackout mags. Quality options can be found for as little as $15 (or less with a decent sale) and you should have no fewer than 5 mags for every gun you own, so there’s really no excuse not to stack them deep. Usually, the pricier the stick, the more durable and versatile the materials, but a $15 magazine, like the Magpul Gen 3 PMAG, will get you a long way.
Don’t be fooled by gimmicky mags with strangely high price points: even the most proven .300 Blackout mag shouldn’t cost you much more than $20. Just be mindful of laws pertaining to high-capacity magazines in your area to ensure any magazine you decide upon isn’t violating any local statutes.
How we selected these products
When reviewing guns or gear, we get our hands on as many products as possible, but there are times when certain products or categories are a real challenge — be it availability, cost, or simply a lack of resources — we can get stymied going hands-on with all the potential candidates. Plus, the magazine category is freaking huge, so rather than present a never-ending list of all the magazines that work with a .300 Blackout we selected those which we felt best represent the price points laid out above — giving you a solid representational list to serve as a jumping-off point for your own research (you are going to do you own research, right?)
To avoid disappointment or steering you in the wrong direction, we bolster our own experience with conversations with experts, comb through reviews on retailer sites & sales data, review industry publications, other blogs, and otherwise surface the best information available.
We aim for all thriller, no filler, as they say.
When considering dedicated .300 Blackout magazines, you have options.You can keep using your 5.56mm magazines, but identifying .300 BLK from 5.56 will be difficult without a means of avoiding cross-loading and the damage that can do to yourself or your firearms.
With a little bit of forethought, this can be done with something as simple as a paint pen and a few minutes of your time.
A better solution is picking up some dedicated .300 Blackout magazines; our favorite manufacturers already make many options that will work well and are dedicated to .300 Blackout. However you solve for it – good luck at the range and stay safe!
- Magpul, Magpul Dot Matrix Diagram
- Sporting Arms and Ammunition Manufacturers’ Institute, Inc., Voluntary Industry Performance Standards for Pressure and Velocity of Centerfire Rifle Ammunition for the Use of Commercial Manufacturers, December 14, 2015
- C.I.P., 300 AAC Blackout, May 18, 2016
- AR15.com, Magpul feed lips warping or cracking