The 300 AAC Blackout delivers

what if you could take your AR-15 and:
  • Run a superior cartridge to the 5.56 without new mags, new bolt, new receivers?
  • Fire subsonic and supersonic rounds without adjusting the gas block and switch between the two with just a mag change?
  • Deliver more muzzle energy from a 10.5″ barrel than a 5.56 out of a 16″ barrel?
  • Not suffer from projectile tumble out of a short barrel?
  • Run a cartridge that was specifically designed to perform using a suppressor and subsonic ammo?
  • Cut down some of that 5.56 range brass you have laying around into something different?
Enter the 300 AAC Blackout: a modern cartridge for the modern sporting rifle.



A 7.62 cartridge that works perfectly on the AR-15 platform with many added benefits: more stopping power than 5.56, a flatter trajectory than 5.56, better suppressed performance and better performance from a short barrel to name a few. Also there is only one hardware difference from the 5.56 configuration – a 7.62mm barrel. This is a simple way to define the 300 AAC Blackout. If you are a fan of the most popular modern sporting rifle in America (we only use the ‘A-word‘ when putting it in the proper context along with the other lies of the Civilian Disarmament agenda). 

Being a person who appreciates things that are new and cool and enjoys being an early adopter with many technologies it makes sense that I would leap into the world of one of Advanced Armament’s (AAC) greatest achievements: the 300 WTF – officially known by the somewhat cooler name 300 AAC Blackout (aka 300BLK on the brass or simply 300 Blackout). There have been previous attempts to leverage the AR-15 platform for calibers other than 5.56 NATO that have resulted in dubious results (6.8 SPC, 6.5 Grendel, etc.) The impetus of the BLK was a little different : the US Government approached AAC with a specific list of requirements for a new, highly reliable .30 caliber (aka 7.62 mm) solution for the AR platform. Thanks to the good people at AAC I can elaborate: 

  • Create a reliable compact 30-cal solution for the 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 7.62×39 ballistics
  • Provide the ability to penetrate barriers with high-mass projectiles
  • Provide all capabilities in a lightweight, durable, low recoiling package

Yep- as bullet point 2 notes, prior attempts required the use of different bolts, different magazines, etc.- stuff that increases the complexity and annoyance of adapting your existing AR hardware to the new caliber. That’s a big expense for the DoD when you think about the logistics of all the mags and rifle components they have on hand for the M4s.

Why not just build a mutant AR that ran on the ammo of its arch-nemesis- the 7.62×39(AK-47) round? It sounds like a good idea and it appears that AAC gave it a whirl since they offer these enlightening data points:

  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

Not surprisingly the wildcat craze (people who enjoyed experimenting with nontraditional handloads in affordable calibers) of recent years led to some research that paid off. The 300 Whisper, .222 and 300 Fireball never were standardized enough to get a SAAMI approval- which the 300 BLK has achieved. However those wildcat efforts proved that it could be effective to send a heavy projectile at lower velocities and deliver more energy on impact that traditional high-velocity rounds like the 5.56. How much heavier? How about 220gr projectiles from the BLK vs 65gr projectiles from a 5.56? It’s almost too bad that the working title for this project didn’t stick: since the goal was to combine and standardize the best of the 300 Whisper, .222 and 300 Fireball this effort was affectionately known as the 300 WTF.
the mag looks funky compared to one loaded with 5.56, doesn’t it? stay tuned for more ravings on my new favorite rifle!

2 thoughts on “The 300 AAC Blackout delivers

  1. Pingback: Internet reloading recipes- a cautionary tale | kR-15: info and resources for firearms enthusiasts

  2. Pingback: AR Pistols: fireballs and headaches | kR-15: info and resources for firearms enthusiasts

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