5 Best Magazines for 300 Blackout


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January 2, 2023

The .300 Blackout has become one of the most popular chamberings for the AR-15 platform in recent years. Born out of a need for a specialized close-combat round for special operations units, the .300 AAC Blackout has become wildly popular for the AR-15 platform – and with good reason.

In subsonic AR systems, it offers higher ballistic performance and stopping power than the normal 9mm (the most popular subsonic SMG round), and it may be used with standard 5.56 magazines.

Because the case dimensions are similar enough to work in both, the .300 Blackout is a good choice. And because it’s such a good choice, there are many options on the market for it, making the search for the right fit a bit difficult and sometimes overwhelming.

But it doesn’t have to be. We are here to help you sort through all your possible selections and find the perfect magazine for your .300 Blackout rifle.

Best Magazines for 300 Blackout

Magpul PMAG 30B GEN M3

magpul pmag 30b gen m3

For every caliber, the Magpul GEN M3 is a go-to magazine, and the.300 BLK mag is no exception. The.300 BLK variant, like its smaller-calibrated siblings, has all of the wonderful Magpul GEN M3 features, including the crush-resistant polymer and aggressive front and rear texturing. Impact and crush resistance, as well as anti-slip and anti-tilt technology, make these magazines among of the most robust and well-designed rifle magazines available.

Cross-loading is reduced with these Pmags, which include a distinguishing rib design, back texturing on the magazine body, and an easily removable, compact floor plate. They also have the GEN3 paint pen dot matrix, which allows you to identify.300 Blackout on the magazine.

D&H AR-15 20 Round 300 AAC Blackout Magazine

d&h ar-15 20 round 300 aac blackout magazine

D&H keeps cross-loading at bay with a simple approach: incorporate a visual indicator of the caliber on the magazine from the factory, rather than opting for an aggressive front texture or particular ribbing.

The D&H magazines have a 20-round capacity and a bright red follower with a uniquely-calibrated spring to assist follower/spring tracking and feed the heavy.

They’re composed of high-quality black anodized aluminum for years of use and a secure fit in any AR magazine well. The factory’s addition of the caliber on the magazine is good, and it seems more consistent than a do-it-yourself approach with a paint pen.

Keep in mind that while aluminum magazines are tough, they can bend and dent rather than break. That being said, it’s always a good idea to check the feed lips on aluminum magazines every now and then to make sure they’re still in excellent form, especially if they’ve been dropped.

Magpul Pmag 20 Round M3

magpul pmag 20 round m3

A proven technique to avoid cross-loading is to vary the design of the magazine. That’s what you get here: this 20-rounder from Magpul is shorter than the 30 rounder, making it easy to differentiate.

The 20 rounder has all of the amazing Pmag features, but it’s a few inches shorter, making it easier to hold. If you want to stick to Magpul products, add some visual markers like a specific caliber in the DOT matrix, and you’ve got yourself an excellent option.

Hexmag HX40 Series 2

Most AR owners keep a large number of black Pmags on hand – a dozen or more is not uncommon. Getting a new Pmag and converting it to.300 Blackout might not be the greatest option.

Many shooters will use just certain types or brands of magazines for certain calibers. Calibers are separated in this manner to eliminate confusion and promote safety by making it simple to match a given caliber with the appropriate magazine.

These Hexmags have a hexagonal texture across the magazine, a handy red follower, as well as a matching red button on the bottom to view the floor plate, and are priced similarly to the Pmag.

These small details make it less likely that you will misidentify the magazine, making it well worth your time to investigate. Cross-loading can be avoided by using different magazines for each caliber. For example, Hexmags for.300 BLK and Pmags for 5.56mm.

Magpul M3 Windowed Pmag

magpul m3 windowed pmag

Most Blackout owners have black magazines, so color choice and changes plus adding a transparent window to check the remaining rounds will help minimize confusion and make the magazine even more useful for.300 BLK bullets.

Because these are conventional 5.56mm Pmags, it’s a good idea to use a paint pen to clearly demarcate the intended caliber if you’re not going to use the color of the magazine itself as a differentiator.

Remember, the goal is to provide as many visible and tactile clues of the intended caliber on the magazine as possible, and we believe these succeed admirably. The window can also be used to keep track of the available ammo.

What To Look For

Can You Use 5.56 Magazines?

In a rifle chambered in 300 BLK, you can use 5.56 AR-15 magazines with 300 Blackout ammunition, although magazines made expressly for 300 Blackout can increase performance and reduce frequent reliability difficulties. This is especially true when utilizing slightly longer and heavier subsonic ammo, as these rounds have more difficulty in 5.56 mags.

It shouldn’t need to be said, but just to be sure, never use a 300 BLK cartridge in a rifle chambered in another caliber, such as 5.56, as this can result in catastrophic failure. While you presumably already know this, designating and marking magazines specifically for 300 BLK to avoid unintentionally loading them into the wrong rifle is a good gun safety regulation to follow.


Steel and aluminum alloy existed long before polymer. In some major ways, both have their own sets of advantages.

Nonetheless, it appears that polymer has a significant advantage in the majority of circumstances. It’s a more adaptable substance that can withstand a lot of abuse. Because of this, you should always keep in mind which sort of material you prefer for your magazines: polymer or even steel aluminum, or other types. 

But, yes, you should probably pick polymer. The weather resistance is significantly superior here. But if you can, you should pick a magazine that combines multiple elements. 

The feed lips of the magazine are where it counts. A component made of reinforced steel is less likely to warp than one made of polymer. This isn’t just an issue of personal taste; it’s about what performs best in the long run.

The most important thing to look for is any concerns with tolerance stacking. It’s a problem that most polymer magazines have because they don’t specialize to any certain type of AR.


Several factors can aid in comparing and contrasting the quality of distinct models for your 300 Blackout. For starters, there’s the circular capacity. Typically, 10-, 20-, and 30-round magazines are available.

However, 32-round 5.56 mags are also an option for your 300 BLK rifle. It all comes down to your preference and how much you trust the performance of a 5.56 mag with 300 BLK ammunition.

For some users, the greatest blackout magazine may come down to grip. You don’t always fire in the same stress and weather situations. Patented internal geometry or a sophisticated follower may be less crucial than a superior grip.

Many other owners place a high value on all-around visibility. You  can get away with using windowed magazines on occasion but you may prefer see-through magazines. Nothing gives you a more unfettered view of your rounds than this.

Keep in mind, however, that not all translucent polymer magazines are created equal in terms of long-term durability. The manufacturer’s experience usually comes into play at this point.

Last but not least, you’ll need something that’s simple to reload and disassemble for maintenance. Only a few of the 300 BLK magazines, in my opinion, meet expectations in this area.


Most magazines are inexpensive and plentiful, and .300 Blackout magazines are no exception. There are quality options for as low as $15, or less with a good deal, and you should have at least 5 mags for each rifle you own, so there’s no reason not to stack them high. The more expensive the mag, the more robust and diverse the materials, yet a $15 magazine will last a long time.

Make sure that you are not deceived by gimmicky magazines with astronomically high prices because you really don’t need to spend an arm and leg to get a good, reliable magazine for your Blackout. 

Bottom line: You shouldn’t have to pay much more than $20 for a 300 Blackout mag and you will not find any wildly expensive magazines on our list.

Every product is hand selected by our editors. We may receive commissions on purchases from a link.

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