The 300 AAC Blackout® (300 BLK) or 7.62×35 gives you options not found any other factory cartridge for the AR-15/M4 platform. The cartridge was developed to provide improved performance from the AR platform with only a barrel change, using standard magazines, bolts and gas impingement systems.

The design parameters of the 300 BLK make it an ideal round for shorter barrels, where the 5.56 NATO is especially lacking, and for suppressed applications. Supersonic loads provide ballistic performance approximating that of the 7.62×39, while subsonic loads vastly outperform the 9×19 NATO for suppressed applications.

Although the 300 BLK was developed around standard AR-15/M4 magazines, they were designed for the 5.56 NATO limiting the performance and compatibility. While some 300 BLK rounds function reliably in 5.56 NATO magazines, others don’t interface correctly with the contact areas of the magazine. Dust and fouling from blow back exacerbate the problem, especially with some of the subsonic and monolithic-bullet rounds, creating side pressure induced friction, slowing stack movement.

Given the wide variety of projectile weights and shapes potentially decreasing overall reliability, a dedicated 300 BLK magazine designed specifically for the cartridge is needed. With the popularity of the 300 BLK, a dedicated PMAG® for the cartridge was a logical step for Magpul®.

The patent-pending Magpul PMAG 30 AR 300 B GEN M3 (300 BLK PMAG) is a dedicated, purpose-built magazine for AR pattern rifles chambered in 300 BLK. It has a 30-round capacity and features an optimized internal geometry that accommodates the wide variety of bullet profiles used in 300 BLK cartridges.

Magazines that will be employed with 300 BLK must need to be clearly differentiated from magazines that will be used for 5.56 NATO. The 300 BLK PMAG has a distinct rib pattern to provide the shooter with both a visual and tactile difference from other PMAGs to clearly differentiate it from them to mitigate dangerous cross-loading issues.

If you chamber a 300 BLK round in a 5.56 NATO gun, it can go into battery by pushing the bullet back into the cartridge case. Firing the round will result in catastrophic consequences. The easily identified rib pattern of the 300 BLK PMAG helps avoid this mistake.

The 300 BLK PMAG has all of the outstanding features of the GEN M3 line, including Magpul’s next generation impact- and crush-resistant polymer, aggressive front and rear texture, an easily removable slim floorplate, a paint pen dot matrix for marking and identification, over-travel insertion stop and a dust/impact cover that also doubles as a go/no-go gauge.

All of the GEN M3 line features lower profile ribs than previous generations. The slightly slimmer profile provides better compatibility with tight double and triple magazine pouches.

And like all PMAGs, the 300 BLK PMAG features a long-life Mil-Spec stainless steel spring, patented four-way anti-tilt follower and constant-curve internal geometry for reliable feeding.

All of the Magpul PMAG GEN M3 accessories work with the 300 BLK PMAG, including the MagLink® , Ranger Plate™, Original Magpul®, Minus 5 Round Limiter and Minus 10 Round Limiter. The Round Limiters are intended for temporary capacity reduction only and won’t make a banned magazine legal.

Magpul is a perfectionist when it comes to its products. The 300 BLK PMAG underwent a lengthy development and testing process before going into commercial production.

The performance of the 300 BLK PMAG has been flawless. I have used the magazines in a variety of different 300 BLK platforms and with a wide variety of 300 BLK ammo. They have become my go-to magazines for the 300 BLK. They’re outstanding magazines.

The 300 BLK PMAG 30 AR 300 B GEN M3 has a MSRP of $15.95. As of this writing, it’s only available in black amd without a window. As with all Magpul products, it’s designed and made in the USA. Magpul stands by its products. Should you ever have a problem with a Magpul product, the company will make it right.

Material Disclosure

I received this product as a courtesy from the manufacturer so I could test it and give my honest feedback. I am not bound by any written, verbal or implied contract to give this product a good review. All opinions are my own and are based off my personal experience with the product.

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