The 300 Blackout has become one of the most popular rounds in the industry due to its direct compatibility with existing AR-15 rifles. That compatibility is in large part due to the design of the 300 Blackout upper being able to be used with standard 5.56 AR15 parts.
The .300 Blackout is the result of what current conflicts have taught us about the modern battlefield and urban gunfights. To be effective, you need a hard-hitting, compact, and quiet gun that will own 0 to 300 yards. The AR-15 chambered in 300 Blackout vastly outperforms the 5.56 NATO in this matter.
This adaptability makes it possible to convert your 5.56 AR-15 into a 300 Blackout with nothing more than a swap of the upper receiver. No ATF paperwork and no professional gunsmithing. That’s it. Keep it simple stupid.
Why You Would Want a 300 Blackout Upper
Besides the easy conversion from 5.56 to 300 Blackout, the 300 Blackout round does outperform the 5.56 in a few areas.
First, the 300 Blackout is a very versatile bullet with weights ranging from 110 grains to 220 grains. The 110-grain rounds are supersonic whereas the 220-grain rounds are subsonic.
The 220-grain round is much easier to suppress, and much quieter when suppressed. The 300 Blackout round also reaches peak ballistic performance put of a 9-inch barrel whereas the 5.56 requires a 20-inch barrel to reach peak ballistic performance.
Best 300 Blackout Uppers
Now that you’re ready to make the move, let’s cover some of the best 300 Blackout Uppers available to buy.
Maxim Defense PDX Upper Receiver Group
The Maxim Defense PDX U.R.G is built to handle the fierce demands of the Tier 1 community and is designed to install on any Mil-Spec lower receiver.
The PDX U.R.G. is also equipped with Maxim’s HATEBRAKE Muzzle Booster. This patent-pending device significantly reduces recoil, decreases the flash signature, and pushes gasses and concussion waves downrange away from the operator improving overall execution.
At just 14" in overall length, the PDX U.R.G. is the ultimate choice for when concealment and personal defense is non-negotiable.
At the heart of the PDX KIT is our Maxim SCW system. This patent-pending design cuts down the length of the stock to 4" and offers an integrated BCG with interchangeable buffer weights to give you the flexibility to maximize performance and versatility without sacrificing functionality or form.
The PDX KIT is also equipped with Maxim’s HATEBRAKE Muzzle Booster. This patent-pending device significantly reduces recoil, decreases the flash signature, pushes gasses and concussion waves downrange away from the operator improving overall execution. The PDX Kit uses a Direct Impingement system.
The PDX Kit comes with everything you need to turn your lower receiver into a Maxim Defense PDX.
Aero Precision 300 Blackout Upper
Aero Precision is one of the best companies in the industry for modern, high-quality AR-15 rifle builds and AR-15 parts. The M4E1 300 Blackout Upper is available in 8", 10", and 16" barrel configurations.
A 10-inch barrel on an AR pistol or SBR rifle is perfect for the ballistics of 300 Blackout. These 300 Blackout uppers all feature different-length handguards and are all equipped with a standard A2 muzzle brake that’s been proven efficient and effective.
These Aero Precision uppers all boast a pistol-length gas system that works perfectly with 300 Blackout. Additionally, these are outfitted with Keymod rail systems for easy mounting of lights, lasers, sling mounts, and other accessories.
Magazines: Each PDX ships with one 20rd magazine (7.62x39mm 20rd CPD mags, 5.56NATO 20rd DHL, .300BLK 20rd Lancer Systems)
Is it The Best of Both Worlds?
Back in 2017, the Bureau of Alcohol, Tobacco and Firearms (ATF) ruled that an AR-15 platform with a short barrel and an arm brace did meet the requirements of a pistol. Although the AR Pistol Laws have become blurry over the years, Maxim Defense has ensured its pistol platforms meet or exceed the requirements.
The Maxim Defense PDX falls under the same classification as guns like the Glock 19 and SIG Sauer P365, but the advantages of an AR pistol chambered in .300 Blackout over conventional pistol calibers are pretty obvious.
With either supersonic or subsonic ammunition, .300 Blackout exceeds the energy levels of a .45 ACP, and the capacity of an AR pistol platform far exceeds that of a full-size handgun such as the Glock 19. Additionally, with the use of an AR pistol brace and a red dot optic, the accuracy far exceeds that of a handgun.
Simply put, The 300 Blackout PDW is a better home defense weapon than any handgun.
The obvious advantage of an AR pistol is the compact size. With its 5.5" barrel and overall length of 18.75", the Maxim Defense PDX fits easily inside a backpack for concealed carry. That makes the PDX a more versatile defensive option than a full-sized AR rifle, and it still falls under the legal definition of a pistol.
Built to the Highest Standards
Maxim Defense firearms stand out in a crowded AR market because they’re built to the highest standards, and the Maxim Defense PDX is no exception. Both the upper and lower mil-spec receivers are CNC machined from 17-4 Stainless Steel, 7075 and 6061 Aluminum. Additionally, the HK height rail created a more rigid upper receiver. The PDXs pistol-length direct impingement gas system is designed to run a variety of .300 Blackout ammunition reliably.
The PDXs 5.5" Nitride Coated barrel has been tested for unmatched durability. The .300 Blackout PDX comes with a 1:5 barrel twist rate, which makes it ideal for shooting a full range of heavier 300 Blackout ammo through the short 5.5" barrel. The PDX will run both supersonic and subsonic ammunition with or without a suppressor.
It’s clear that Maxim Defense designed its PDX to be as shooter friendly as possible. The muzzle is topped with their HATEBRAKE that’s made from 17-4 H9000 stainless steel and DLC (Diamond-Like Coating) for maximum corrosion resistance, and it effectively channels muzzle blast away from the shooter while decreasing the flash signature, significantly reducing felt recoil, and increasing the overall accuracy of the weapon.
At the heart of the PDX is our newly developed Maxim SCW stock system. This patent-pending system cuts down the length of the stock to 4". The integrated BCG with interchangeable buffer weights gives you maximum performance and versatility without sacrificing form and functionality.
Not all pistol braces are created equal, and Maxim Defense opted to outfit the PDX with its SCW Series Pistol Brace. No buttons to push, just pull the brace to deploy. At its most collapsed position, this SCW brace only adds 4.0" to your AR15. At full extension, the Maxim SCW brace reaches 8.8 inches. With 5 total positions, you can adjust for maximum comfort.
Built with rapid deployment, purpose-driven materials, and the functionality you need, the Maxim Defense SCW brace is simply the shortest, most thought out, versatile, and durable SCW brace on the market.
Level Up Your Personal Protection
At just 18.75" in overall length, the Maxim Defense PDX fits easily into a standard-size backpack, and since it weighs just 5.9 pounds empty, it isn’t a burden to carry when it’s fully loaded.
Carrying the PDX in a pack also is an ideal setup for those who enjoy the outdoors and getting off the beaten path. It provides you with a level of protection against the associated risks of being far from help.
In addition to carrying the PDX during outdoor activities or keeping it inside your go-bag during daily commutes, it’s a blast just to take the range and you’ll more than likely get a few noticeable glances once you pull this bad-assery from your bag.
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