.300 AAC Blackout

I read about the The .300 BLK by AAC (Advanced Armament Corp.) around September 2010 and have been watching the reviews of this weapon before I wrote a post on it

The round was designed by AAC in 2010 and designed around the M4 Carbine platform  (short barrel AR-15 rifle) One weapon and caliber replacing the standard M4 This upper receiver group uses a standard  M4 bolt and Bolt Carrier Group.  This allows Military or Law Enforcement to take the standard M4 and just replace the barrel to the new .300 AAC blackout.

The project goals were:

  • Create a reliable compact 30-caliber solution for AR platform
  • Utilize existing inventory magazines while retaining their full capacity
  • Create the optimal platform for sound and flash suppressed fire
  • Create compatible supersonic ammo that matches 7.62×39mm ballistics
  • Provide the ability to penetrate barriers with high-mass projectiles
  • Provide all capabilities in a lightweight, durable, low recoiling package

Reasons the 7.62×39 was not considered:

Extreme cartridge taper
• Reduces reliability of feeding in AR Magazines
• Reduces Magazine capacity
• Cartridge taper induces considerably higher bolt thrust-
exacerbating the AR Bolt’s weaknesses
• Requires a larger Bolt Face which reduces Bolt Locking Lug strength-
exacerbating the AR Bolt’s weaknesses
Limited projectile selection
• 0.311″ diameter not a common option in most modern bullets
[As stated on the .300 AAC Blackoutwebsite]


The .300 Blackout uses standard AR-15 magazines and with cartridge size allows for the capacity of the magazine to be unchanged in round count.

The 300 AAC BLACKOUT 123 grain ammunition matches the ballistics of the 7.62x39mm AK and has 37% more energy than 5.56mm M855 when either are fired through a short barrel.

AAC commented saying “its hard to support a wildcat round (such as the .300 whisper) when load data is all over”.

The 300 AAC BLACKOUT  upper receiver is compatible with all AR-15 lowers

300 AAC BLACKOUT was approved by SAAMI on January 17, 2011.(Sporting Arms and Ammunition Manufacturers’ Institute)

  • .300 BLK is going for approximately $20 for 20 rounds ($1 per round)
  • 7.62×39 is going for approximately $5 for 20 rounds ($0.25 per round)
  • .223/5.56NATO is going for approximately $5 for 20 rounds ($0.25 per round)

300 AAC BLACKOUT 125 grain plastic tip, 300 AAC BLACKOUT 125 grain match, 300 AAC BLACKOUT 220 grain subsonic, 5.56mm NATO, 7.62x39mm
L-R The 300 AAC Blackout plastic tipped, left, compared to 300 AAC BLACKOUT 125 match, 300 AAC BLACKOUT 220 subsonic, 5.56mm, and 7.62×39mm.

Tagged . Bookmark the permalink.