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The Curious Case of 300 Blackout

The intermediate cartridge known as 300 Blackout or 300 AAC Blackout carries with it a bit of mystery and a short history of rapid acceptance across various shooting traditions. The dates of its development coincide with the proliferation of AR-style firearms after the sunset of the Clinton Assault Weapons Ban resulting in the quick adoption by hunters, reloaders, and manufacturers, as well as those concerned with self-defense. At the same time, the round has been compared to 5.56 NATO and 7.62×39 by both enthusiasts and professionals. From the 30,000-foot view, the first testimony to the merits of the cartridge begin at how well it has taken root in firearms culture.

fort scott 200 blackout

Mutual Interest Origins

Multiple influences contributed to the origin of the 300 Blackout cartridge. The rise of Special Operations during the Global War on Terror increasingly focused on night capability. Their influence over the private industry demonstrated itself as short barreled rifles, suppressors, and eventually, night vision took the market by force, cascading into private interests on maximizing performance. The limited ability for Night Vision Goggles to clearly identify possible enemy combatants at distances beyond 300 meters, combined with the inherent increase in Close-Quarters Battle type engagements drove development to look at new cartridges that could combine the best of both pistol and rifle caliber cartridges.

300 blackout ammo

Advanced Armament Company and Remington Defense were able to use the M4 or AR-15 form factor by trimming a 5.56 case down to accept .30-caliber projectiles. A 5.56 AR-15 could be swapped into the heavier .308 caliber round by simply replacing the barrel (and the suppressor, depending), as the remainder of the components were cross-compatible.

The idea of a slow-moving, heavy round has been around since the 60's, and Soviet engineers adopted the concept early with the 7.62×39 round. JD Jones pioneered much of field earlier with the 300 Whisper cartridge, which furthered the concept of a low-visibility use firearm with a cartridge specific to that purpose.

300 Blackout vs 5.56
Left: 300 Blackout, Right .223 Remington.

Where military interest initiated the series of events that resulted in the 300 Blackout round, the civilian market played a role in solidifying the success of the cartridge. A key feature of the round is its versatility as either a supersonic or subsonic load. Where the faster option optimizes ballistics, the slower subsonic ammunition performs exceptionally out of a suppressed firearm, giving pistol ammunition a run for its money.

Reloading enthusiasts benefitted from the generous adaptability of the round. From re-sizing 5.56 brass to fit the larger projectile, to tailoring their own ideal balance between powder and bullet weight, one further layer of personal tuning could be enjoyed by the shooter like a well-developed family recipe.


The 6th Edition of the Ammo Encyclopedia describes the 300 AAC Blackout cartridge as follows:

The .300 AAC Blackout is a new centerfire rifle cartridge designed to offer fleximble ballistic performance for the modern soldier. There were three goals in developing this new cartridge: it must offer subsonic terminal ballistic perfomance superrior to the 9mm Luger cartridge, it must offer supersonic terminal ballistic performance as good as or better than existing 7.62x39mm ammunition, and it must fit in M-16 magazines and rifles with minimal modification.

Michael Bussard, et al. Ammo Encyclopedia, 6th Ed. (Blue Book Publications, Minneapolis, MN), p633.

From inception, the objective of 300 Blackout was for it to be evaluated when fired from a suppressed firearm. The versatility of 300 BLK requires that it be compared to different cartridges depending on the load. While Bussard mentions the three goals in his description, 300 AAC Blackout is most often compared to 5.56, for both military and civilian use.

Evaluating the round typically takes one of two different directions: direct ballistic performance, and circumstances surrounding fielding and use.

300 blackout measured
(actual size from left to right) 5.56x45mm XM193 55gr., 300 AAC Blackout 125gr. OTM supersonic, and 300 AAC Blackout 220gr. Subsonic

Both rifle caliber and pistol caliber carbines attempt to balance overall firearm size with the performance of the firearm. Generally speaking, the longer the barrel, the greater velocity of the projectile, with diminishing returns dependent on the load. Compared to other projectiles, 300 Blackout performs exceptionally well out of an 8 to 10-inch barrel, especially when suppressed.

This plays well with the popularity of 30 caliber suppressors, where some have even been developed specifically to handle the pressure of subsonic 300 Blackout ammunition, but not supersonic.

For civilian users, the greatest prohibitive factor of using 300 Blackout for hunting medium game is certainly the cost of ammunition. Still teetering between special use and common cartridge, ammo manufacturers are saddled with the greater cost of components and are aware that time spent assembling 300 AAC Blackout means less time working on other, more popular cartridges. The ouroboros relationship regarding 5.56 NATO versus 300 Blackout is that the prior has become more popular due to availability because it has been the choice of the military for decades before the latter was conceived, and as a result, is more readily available to consumers as well. Betting men are still debating over if or when the latter will become more dominant.

Loose Rounds

The 300 Blackout cartridge is best fired from a suppressed, short-barreled AR-style firearm at distances shorter than 400 meters if supersonic ammunition is used, and less than 200 if subsonic. The ballistic performance paints the round as esoteric and eludes to the secretive nature of special operations. At the same time, to the civilian user, it serves as a versatile hunting and self-defense round, as well as an entertaining reloading option, as long as they can find the components.

300 Blackout vs 5.56
With the near universality of parts, one of the greatest dangers is loading a 300 Blackout round into a gun chambered in 5.56. Isolating magazines is not merely advised, it is absolutely necessary.

Where many other cartridges have died on the vine, 300 Blackout has survived past adolescence to become a common caliber in America. Market acceptance, which sometimes precedes, sometimes follows Military adoption, typically determines the survival of a new caliber, and because of its versatility and performance, Blackout is here to stay for a while.

A sign of the times, 300 Blackout signifies special application and general acceptance at the same time, due to the commonality of parts with 5.56 AR-15s. The 300 blackout owes its existence to the modularity of America's Rifle.

For what's new from Advanced Armament Company:

More on 300 Blackout

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