The .300 Blackout rifle cartridge is also known as 300 AAC Blackout, 300 BLK, and 7.62x35mm. Its design comes from the idea to develop a cartridge more powerful than AR-15’s native 223/5.56, with ballistics similar to those of the 7.62x39mm. This new cartridge had to work reliably with both supersonic and subsonic ammo, in the barrel that is less than 16 inches long. When fired through a suppressor, .300 Blackout bullets give a silent, yet powerful rifle. This ammo can be used for hunting, target shooting, as well as for home defense. Learn more about 300 BLK

300 Blackout Ammo

The .300 AAC Blackout is an intermediate cartridge designed to share ballistics similar to those of the 7.62x39 (AK-47 cartridge). It was developed for use in the M4 carbine and can be fired from a standard 5.56mm AR by only changing out the barrel.

It is also known as:

  • 300 BLK
  • 300 AAC Blackout
  • 7.62x35mm

Advanced Armament Corporation collaborated with Remington Defense to develop a .30 caliber cartridge that would surpass the performance of 5.56mm ammo. This long-contemplated idea of replacing AR-15s native 5.56mm came to life after United States Government launched an international military campaign aka global war on terror after 9/11, and our troops found themselves in unfamiliar geography and unknown situations. The demand for a cartridge that has was more powerful and more silent lead to AAC developing 300 Blackout ammo for special operations forces, using a 5.56mm case cut down to fit a 30- caliber bullet.

When was 300 BLK invented?

Although AR-pattern rifles and carbines had been previously chambered in different 30 calibers, feeding issues were present with each attempt. Many ammunition manufacturers had tried and failed, including Colt Firearms. The solution was found thanks to wildcatters. One of the wildcatted cartridges - .300 Whisper served as a concept to get to the final result, and the one to be submitted to SAAMI. Development began in 2009, with the cartridge approved by SAAMI in 2011.  

What’s the difference between 300 AAC and 5.56 / .223? 

Even though both rifle cartridges are suitable for target shooting, hunting, and home defense, there are a few differences between them.
300 blk bullet is stubbier, thicker, and heavier. 5.56mm NATO requires a longer barrel length, at least 12”. Once you add additional few inches that suppressor takes, it becomes impossible to get a powerful, yet short rifle.
On the other hand, 300 BLK works best in shorter-than-average barrels, which makes it super suitable for suppressed use. 300 blackout works reliably with both supersonic and subsonic ammo, but it shines when using subsonic and a suppressor, giving you a quiet and powerful bullet.
5.56 has a faster velocity and shoots flatter, while 300 penetrates through more material.  

300 BLK overcomes some of the shortcomings of larger calibers while providing the AR 15 with the possibility to shoot a larger round, with only switching the upper receiver.  

.300 AAC Blackout round military use


The first formal adoption of 300 AAC happened in July 2015, when the Netherlands’ defense material organization bought 195 carbines chambered in this round. These integrally suppressed 300 BLK carbines were purchased for the Dutch Maritime Special Operations Force and modified to for use with ballistic visor helmets. 

United Kingdom 

Ministry of Defense ordered the supply of 300 Blackout ammo on a five-year contract, including the option to extend for an additional five years. The government noted the previous use of this round. 

United States

This round has not yet seen wide use in American Special forces, although SOCOM started using it in 2017, considering offers on how to modify 5.56 to accommodate 300 AAC rounds.   

Popular 300 Blackout Ammo Brands 

  • Remington
  • Fiocchi
  • Hornady
  • Magtech
  • Aguila
  • Sellier & Bellot
  • Barnes 

Which guns use 300 BLK Ammo?

A few popular models, including top-shelf rifles using with both supersonic and subsonic ammo, rifles widely used for home defense, hunting, or target shooting:
  • Daniel Defense DDM4
  • Wilson combat protector
  • IWI-US Tavor X95
  • Springfield Armory Saint
  • Ruger Ruger American Ranch Rifle
  • Ruger AR-556
Our selection is in no particular order regarding the best 300 blackout gun. Use this list as your starting point when searching for a weapon that suits you best.
Scroll to top