What Is A 300 Blackout?

The 300 Blackout, famously known as 300 BLK or 300 AAC Blackout, is one of the cartridges developed by Advanced Armament Corporation in the United States. The 300 AAC Blackout is considered the best alternative AR-15 Cartridge available in the market today. Its capability of dropping whitetails and ringing steel targets beyond 100 yards makes it the most excellent option to have. For those who own short barrel rifles of AR-15s, the 300 Blackout cartridge should top your list of cartridge choices.  

It was developed specifically for military purposes as they were searching for a cartridge with better performance than the 5.56 NATO. They also wanted a cartridge compatible with the M4 magazines that would not force them to sacrifice their ammo capacity. The military also wanted subsonic ammo, which will prevent them from suffering from loud noises. This allowed the manufacturer to build off their existing 300 Whisper cartridge, a 300 BLK that met every military requirement. They designed it specifically for use in M4 Carbines. The 300 AAC Blackout was developed to achieve ballistics similar to those of a 7.62* 39 mm cartridge in an AR-15.

These energies are achieved when the AR magazines are used to their full capacity. They are also less noisy as the only sound you will hear is the clapping of your gun’s bolt. If you have been wondering, “What is 300 Blackout?” Read on to learn more about it.

What is a 300 Blackout Caliber?

What is a 300 blackout caliber? You may ask. A 300 Blackout caliber is a caliber designed to increase the Umph of the AR platform in terms of penetration and power on intermediate ranges. The manufacturer's original intent was to come up with a caliber that has accuracy and terminal performance while using standard or subsonic rounds. This caliber is created to withstand the recoil effect as you hold on to your 30 round mag.

A 300 blackout is suitable for hunting due to its .30 caliber bore that can burn to its full potential while in a 9-inch barrel. Its strengths also shine when using silencers or short-barreled rifles or when you need a barrier penetration. You can comfortably hunt with it for over 200 yards as it can quickly cycle subsonic and super ammunition without any modifications. A 300 blackout caliber is perfect for hunting, target shooting, and home defense. You can also use it for your day today for general purposes.

Compared with the 7.62*39mm rounds, the 300 BLK rounds have more energy and a better ballistic coefficient when used with varying loads. 300 BLK rounds have a barrier blind performance. Several calibers have been introduced into the market, but the only one that still stands out is the .300 AAC Blackout. Below are some of the outstanding features of the 300 blackout caliber:-

Subsonic Ammunition

The 300 AAC Blackout utilizes subsonic ammunition, which propels projectiles at a slower rate of more than 1,125 feet per second without causing a sonic boom. If you add a suppressor, your precision rifle fire will become the quietest weapon on the planet. This is because the suppressor will control the explosion of gunpowder. The vast majority of ammo that you will find on the shelves of any nearby sporting goods store is supersonic ammunition.

This means that the projectiles of this ammo travel faster than even the speed of sound, thus creating a sonic boom. If this sonic boom is added to the gunpowder exploding sound, it leads to serious noise after every single gunshot. This is why the 300 Blackout Caliber uses subsonic ammunition.

Terminal Ballistics

Terminal ballistics refers to what happens when a flying bullet hits a target. The wound created by the round of a 300BLK is generally deeper and wider because it utilizes .30 caliber bullets which are fatter, heavier, and shorter. For a single data point, the stouter bullets which have more mass are said to have high ballistics. In all essences, the 300 BLK outshines a 5.56 NATO in terms of terminal ballistics. The 300 BLK cartridge can create some lethal wounds, mostly if you use modern bullet designs. With most bullet designs, there is a shrinking gap between the caliber’s killing power.  It also has a slight inherent edge over most cartridges as it has the advantage of a large caliber projectile.

Exterior Ballistics

Exterior ballistics refers to how a bullet flies in the air. The 300 BLK has a less flat trajectory even though it has a more aerodynamic and sleeker projectile design. This means it travels slower, and thus the slow velocity will not allow you to get a great advantage of the tampered beautiful profile. As a result, the 300BLK sputters out and has a significant drop after 250 yards. Within 200 yards, you will enjoy some reputable accuracy on all your targets.

Barrel length and Twist Rate

It is essential to note that a 300 Blackout burns out the gunpowder quickly, and thus their projectiles can achieve optimal velocity if fired using a short barrel. To build an AR-style rifle using a  300 BLK  is easy as all you will need is readily available. You can decide to convert your existing 5.56 AR-15 to 300 BLK without so much effort. To achieve this, you need to change the barrel but keep the bolt, the lower receiver, and the magazine. A 9-inch barrel is considered an optimal barrel length when making a 300 BLK.

This will make a 300 BLK perfect during a home defense as you maneuver through tight interior spaces. You need to also consider the twist rate of your 300 BLK barrel. Twist rate refers to the rate at which the barrel rifling spins. A ratio of inches for every barrel turn represents the twist rate making one complete rotation.300 blackout pdw

The 300 Blackout Review

The 300 Blackout review requires us to take a look at different dimensions. There are five significant criterias to look at when reviewing a 300 blackout. These include the muzzle energy, caliber projectile, adjustable gas blocks system, unmodified magazines, and the ability to shoot supersonic and subsonic. A 300 AAC blackout has muzzle energy that exceeds an AK-47 and has a .30 caliber projectile. It also uses .30 magazines and an unmodified AR-15 bolt. 

As you should know by now, it utilizes a gas impingement system and is capable of shooting at zero range and close quarters, both supersonic and subsonic. These are the primary features and selling points of the great 300 AAC blackout. It is greatly loved because of its incredible adaptability to fit in a standard AR-15. Regarding probability, the 300 Blackout is often said to have a max effective range of about 460 meters. 

From a 9 inch barrel, the 300 BLK discharges a 125 gram round which has muzzle energy similar to an M855 of an M4 carbine. At 440 meters, it has 5 percent more energy when compared to a 7.62*39 mm sub gun round. The 300 BLK rounds have better ballistic coefficients than barrels of similar length. As much as it is primarily used on an AR-15 platform, you can use it in all other sorts of guns too. This great hunting cartridge gives you accurate and solid energy on the intended target. 

Changing your .223 AR into a 300 BLK will need a simple barrel change. You can utilize a .223 bolt and an AR magazine to make the transition easy and inexpensive. The ability of a 300 BLK to work in a .223 based bolt carrier group increases its versatility. In the current day, most manufacturers offer a bolt rifle for this type of caliber. When using an AR platform, there is always a seamless movement from subsonic to supersonic ammunition. Since it is a great hunting medium, most avid hunters have opted to move to a 300 BLK when hunting inside 300 yards. 

Reloading The 300 BLK and the Bullet drop

When using the 300 BLK brass, you will need less powder compared to a .223, and thus it is cost-effective. Generally, you can fit it in a magazine and load short bullets that work just as well. The 300 BLK allows you to load nearly everything from high-velocity targets and hunting rounds to cost-effective practice ammunition. All these rounds exhibit excellent accuracy. The bullet also drops to about 2 inches while at 100 yards and 4 inches at the 200 yards mark. The drop of a 5.56 bullet is almost half of a 300 blackout bullet at any given range.

What is so special about the 300 blackout?

All other rounds serve a purpose with varying weaknesses and strengths. There have been several replacements over the years for a .223 and a 5.56 mm NATO. The 300 Blackout came and took over the market by providing advantages that are noticeable to all. It was developed to solve the shortcomings of other calibers such as proprietary magazines, ammunition, accuracy, and reliability issues. Since existing cartridges either failed or had some major marginal success and retailing them was problematic, the 300 blackouts came as a savior even to gun retailers.

The reliability of the 300 BKL exceeds that of 5.56 NATO and its equivalents as it offers shooters a more reliable penetration. Most Barrels are equally priced and utilize similar bolt action groups and AR magazines, but their compared ballistics vary. The 300 BLK is special because it does not require a piston system when using a suppressor but rather works better with DI systems. It is also viable for use with hunting bolt rifles and self-defense pistols. Due to its wider range of projectiles, it has become so popular among the shooting community. It has thus become a real money maker for all retailers due to its strengths and broad appeal.

Why is 300 Blackout called blackout? 

Blackout was a name given by AAC to all their premium line of calibers and ammo products. Therefore, when they developed the 300, they decided that it would be part of their premier products and thus gave it  the name “Blackout”. The 300 BLK round got its name from the 300 Whisper. The 300 Whisper round was designed as the name suggests. This round would make a suppressed shot, and its casing was made by stretching out the casing of the 5.56 mm NATO and slightly trimming it down.

The  300 blackout pdw

The 300 Blackout PDW is the kind of pistol you can rely on for personal and home defense. This AR-15 style pistol gives you so much fun when using it. A 7 inch 300 BLK forged barrel provides you excellent ballistics and keeps all subsonic loads in their subsonic state. For shorter barrels, you can testify that the 300 BLK caliber is the best. The PDW has an overall barrel length of 20.25 inches and comes fully equipped with a Maxim Defense Pistol Brace, which allows you to comfortably change the adjustments to suit your needs when shooting your AR pistol. 

This pistol has a 6-inch MFR XL front rail for fast accuracy, reliability, and handling. This front flat rail provides compatibility with a wide range of accessories. The 300 BLK PWD also features an M-LOK with attachment points to help give the shooter a safe shooting experience. Before purchasing it, it is essential to check with your federal and state agencies regarding its legality for use within your jurisdiction.


  • It is an Ultra-Compact platform with a 1:7 barrel twist, making it compatible with supersonic and subsonic loads.
  • It has an independent Ambi GRIP-N-RIP charging Handle, which accommodates both the right and left-handed shooters.
  • It has a linear compensator that directs the muzzle blast to the front of the muzzle threads and allows for the customization of the muzzle device.
  • Maxim Defense CQB or CQB Gen pistol brace and stock has an enhanced buffer systems function to reliably suppress and unsuppressed the subsonic round.

Materials & Construction:

  • Barrel - The barrel is made of Chrome Moly Vanadium Steel and constructed with a Forged Cold Hammer.
  • Gas system - it uses a low-profile gas block that is machined with hardened steel. It also has a heavy coating of phosphate on the popular civilian barrel-length pistol.
  • Muzzle device - It is machined with stainless steel and has a salt bath Nitride finish.
  • Handguard - The CNC handguard is machined with Aluminium and anodized with a Type III hard coat.
  • Pistol Grip is made of a Daniel Defense Grip and a glass-filled Polymer with a soft touch of over-molding.
  • Lower Receiver - it is an enhanced flared Magazine.
  • Upper Receiver - It is made of a Mil-Spec, M4 Feed Ramps, and Indexing Marks.

The best 300 Blackout Lower Receiver

The 300 Blackout AR-15 build is famous for its modularity. The customization offered by an AR-15 platform is one of the primary factors it is very popular among the shooting community. Most shooters prefer to invest in a 300 Blackout lower receiver to customize their weapons. This lower receiver has key components such as a disconnector, trigger, fire selector, and a magazine catch.

It is essential to bear in mind that most 300 blackouts lower receivers have the same bolt, cartridge length, and magazines that make them compatible with most 5.56 and 2.23 rounds. Some of them are also compatible with the 9 mm rounds making them a great option if you want a full custom build. Below we shall look at some of the best 300 blackout lower receivers that will offer you great value for your money.

PSA AR-15 Classic Stealth Lower

The Palmetto State Armory offers this lower and comes fully assembled, ready to be installed with your upper of preference. It is anodized with a Type III hard coat and an M4 lock nut, and an M4 stock. This aluminum grade is heavy-duty and instills confidence in a shooter when they seat the buttstock on their shoulder. It is a high-quality lower receiver with a Mil-Spec diameter receiver. It also has a carbine buffer and utilizes lighter bullets.

PSA-A2- 504399 Rifle Lower Receiver 

This lower receiver has been engineered to be installed easily. Its buttstock has been designed to look like a standard rifle stock appealing to traditionalists who love a classic look. It has also been engineered to be versatile; thus, it fits in a 300 blackout rifle and other AR caliber rifles such as the .223 and 5.56.  It is also a great value pick for those looking for a lower receiver. It is machined with incredibly durable aluminum, the 7075-T6 with forgings of a MIL-A-8625F. It is lightweight and has a nicely padded buttstock which gives a less recoil impact. The PSA -A2 Lower receiver can also be collapsed, making it highly portable and perfect for saving on space during hiking. 

MOE SBA3 Lower Receiver 

The MOE SBA3 lower receiver should be near the top of your list of lower receivers as it has an easy-to-use safety and gives you a natural feeling while using it. This lower receiver is developed using cutting-edge techniques to produce a highly forged MIL-SPEC. Due to the automated manufacturing system, you are assured of consistency in its accuracy and performance at an affordable cost. This makes it a great value option for those who are on a budget.

AR15 300 blackout

The AR 15 300 Blackout is a very competitive product in the market today. When compared to a 5.56 NATO or a .308 Winchester, you can't fail to note their huge differences even though they are functionally identical. These three cartridges utilize similar bullets, such as the Hornady GMX, Winchester Extreme point, and the Nosler E-TIP. However, if you are looking for lightly constructed bullets for varmint hunting, you can use the Hornady V-max, which is common with a .223 Remington cartridge. The Nosler partitions are suitable for big game hunters who use a 308 Winchester or a 300 blackout. These are just but some of the similarities between a 300 blackout and other cartridges. Below you shall find the similarities and differences of a 300 blackout and a 308 WIN, and the difference between a 5.56 NATO and a 300 Blackout.

Is 300 blackouts the same as 308?

The most significant difference between these two cartridges is the size and weight of the bullets they use, even though they have identical functionalities. Most. 300 BLK factory loads utilize bullets in a 78-226 grain range, while most factory loading of 308 Winchester utilizes bullets in a 110-180 grain range. The 308 WIN is considered a better choice for those participating in long-range competitions.

It also has significantly higher power and range when hunting large and medium games. The 300 blackout has a noticeable short barrel, while the 308 has a longer barrel even though they have similar bullet diameters. The 308 WIN utilizes heavier bullets with high ballistic coefficients and thus retains more energy and has a faster velocity than the 300 blackout bullets. The bullets used are not hollow point bullets as they are strictly for military use.  

Combined with a much superior energy retention ability, the 308 Win becomes a better choice. So which is better? If you are after target shooting,  plinking, which is just plain fun or training, you can use the 300 BLK due to its lethality and stopping powers. If you want a cartridge perfect for home defense, you should think of the 300 BLK. Due to the adverse effects of using a loud weapon while at home, having a suppressor that uses subsonic ammo will be ideal for your hearing. High-end loading suitable for a 300 BLK will be essential if you do not care about having an NFA firearm.

What is the difference between 5.56 and 300 blackouts?

There are several differences between a Remington / 5.56mm NATO cartridge and a 300 BLK, even though they share similar case head dimensions. The similar case heads enable them to use the same magazines and bolt carrier group for an M4 or an AR-15. This makes the conversion to be as simple as swapping the muzzle device and the barrel. A 300 BLK has an increased frontal area provided by the larger caliber diameter of a .308 projectile.  Projectiles with a wide diameter tear more tissues than those with a slimmer frontal area, increasing the wounding capacity.

As a projectile flies through the air, the change in drift can make the bullet drop after a few yards. The US military has rated the maximum effective range of an M4 as about 500 meters. Therefore, If we use 500 meters as a benchmark, an M855 bullet round of a 5.56*45 mm NATO will have a projectile drop of 100 inches if fired at 2900 FPS. It will also experience 41 inches of wind drift and 291 ft-lbs while at that distance. This is in contrast to a 300 blackout which is fired at 2220 FPS and if the ammunition weighs 125-grain projectiles.

This illustrates that a 300 Blackout will experience an excellent bullet drop as it is fired at a slower velocity. This is why the 5.56mm NATO shoots significantly flatter at a higher velocity and with less wind drift even though it has half as much energy as a 300 BLK.  The increased weight of an effective round projectile provides more kinetic energy at 500 meters for a 300 BLK and the same kinetic energy at 700 meters for a 5.56 MM NATO. The US Military has calculated that a 300 blackout has a probability of hitting a target at 462 meters, which is a loss of 38 meters compared to a 5.56 NATO projectile that shoots flatter.

An avid shooter should maximize on a higher ballistic coefficient of energy and hit probability inside the 300 meters mark to achieve sleeker projectiles. This can be achieved by selecting a caliber that fits the vast majority of all military operations. Hit probability has some primary factors that greatly influence its impact on the target. These factors include barometric and wind. Shorter barrels also have a slight ballistic advantage compared to longer barrels. Thus velocity reduction on a 300 BLK ballistics does not affect its hit probability as it affects the 5.56 NATO cartridge. 

The other difference between the two is the barrier blind projectile potential. Law enforcement and the military consider the potential of a projectile in becoming barrier blind as a very important factor. Barrier blind is the tendency of a projectile deviating from its patch of trajectory due to encountering an obstacle. Any projectile that has greater kinetic energy will deviate less from its path of trajectory against identical barriers. Therefore, due to a heavy projectile's great kinetic energy, a 300 Blackout enjoys significant barrier blindness against barriers such as a glass windshield, heavy clothing, plywood sheeting, and sheet metal used on vehicle panels. On the other hand, 55, 62, and 68 projectiles used in a 5.56 NATO ammunition cartridge have less barrier blindness. 


Therefore, we can conclude that though most cartridges have similarities, there is always something special that you will find with a 300 blackout. It is lightweight, and its performance spectrum outdoes the other calibers. Thus, when choosing an AR-15, you should consider the 300 BLK. Its ability to offer you a quiet suppressed performance for your home defense should make you rank it at the top of your list of cartridges. Its several technical properties have made it quite remarkable and have fixed the problems its predecessor had. Though most of its primary users are those in special forces, the public should consider putting it into good use as a 300 blackout round was created for them.

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