300 Blackout (300 BLK)

In case you have been living in a cave for the last several years, the 300 Blackout is the sexy new girl on the block.  This article is part one of a new series on the 300 Blackout (300 BLK).  While the cartridge-haters will tell you that the 300 BLK is the answer to a question no one asked it is an interesting option – especially for use with subsonic ammunition and a suppressor.  After all, do we really need much more than .22lr, .45 ACP, and .308?  Variety is the spice of life and the Blackout is growing in popularity.

There is much confusion regarding the .300 Whisper v. .300 Blackout.  In summary:

  • Whisper was developed by J.D. Jones in the early 1990’s by necking up a .221 Fireball to .30 caliber (as a side note, I hunted with a Remington XP-100 in .221 Fireball in the early 70’s – very cool pistol).
  • Blackout was developed by AAC and Remington in 2009 by shortening and necking up a .223 cartridge.  Why reinvent?  The Whisper is not SAAMI certified.  The Blackout is often referenced as the 300 AAC.
  • 300 Blackout has won the PR war and is now pretty much the standard.  “Blackout” was all over SHOT Show and the NRA Convention.  Mainstream companies are manufacturing optics calibrated to 300 BLK ballistics.
Whisper Blackout

Whisper Blackout

Like the 6.5 Grendel and 6.8 SPC, the driving force behind the 300 BLK was the desire to upgrade the standard .223/5.56 rifle.  Full disclosure:  I regularly hunt with a Bison Armory 6.8 SPC II and love it!  The combination of light weight, ergonomics, accuracy, and capacity make it a wonderful gun for hog hunting.  Long-range shooters covet the 6.5 Grendel for its high ballistic coefficient bullets.  So, why the 300 BLK?

Well, consider that Advanced Armament developed the 300 BLK.  What is AAC known for?  Suppressors, of course.  The real difference between the 6.5 Grendel, 6.8 SPC, and the 300 BLK is the latter’s performance with 220 gr subsonic ammunition.  That is one reason why I acquired a 300 BLK rifle – for subsonic use.

We do a lot of hog hunting in Texas.  Hog hunting is an up-close and personal experience.  The best (most fun) way to hunt hogs is on foot, stalk hunting, sneaking up on stock tanks, shooting on the run.  The AR-15 platform with a red-dot type scope is ideal for this scenario!  Shots are usually around 50 yards so velocity deterioration is not an issue.  With the 300 BLK I have the choice of firing the Barnes 110 gr TAC-TX (at around 2400 fps muzzle velocity) or the Remington/PNW Arms 220 gr subsonic ammo.



Second, to be able to dispatch coyotes and test optics at our family farm without disturbing the neighbors.

Part two of this series will focus on the AAC Model 7 300 BLK rifle.

Part three will focus on testing the 220 grain subsonic ammunition with the Templar Tactical ARK30 7.5″ 300 BLK suppressor – which promises to be huge fun!

Part four will be field reports.



14 Responses to 300 Blackout (300 BLK)

  1. Cary Kieffer says:

    Thanks Michael and Lonnie for clearing that up for me. Mike, looks like you got a winner of a topic here. Lots of interaction on it. That’s great. I’ll be staying tuned to this one.

  2. Michael Reyneke says:

    Cary, to answer your questions:

    1. The Blackout seats nicely in any AR magazine just as well as 5.56×45. No complaints from what I have seen.

    2. The 300 Blackout is known to cycle the best in ARs with pistol length gas systems. Bolt cycling IS a known problem, but it all depends on the ammo (subsonic vs. supersonic) and the ‘heaviness’ of the buffer. Most guys will load their own ammo and shoot with lighter buffers to prevent cycling problems. Subsonic ammo runs well in pistol ARs and SBRs, but doesn’t have enough energy to cycle the bolt on the longer gas systems.

    Supersonic loads will cycle in any gas system because there is enough energy. If you plan on hunting big game with the 300, use supersonic. Subsonic doesn’t have enough power to take down the target.

  3. Elliot says:

    @Cary – I feel the same way. I keep hearing about the 300 but have yet to see anyone do a comparison test.

  4. chad says:

    why go thru the trouble of loading 7.62×39 subsonic?

  5. Lonnie says:

    I have heard it said many times the 300 is like a semi-auto 30-30. The advantage over the 7.62×39 is they use all standard AR parts except for the barrel of course. They are very easy to quiet. 180-220 grain or you can shoot without a can with 120-165 grain very nicely. Another advantage over the 7.62×39 round is for the re-loader. The 300 can be made very easily out of 223 brass using small rifle primers. 223 brass is very easy to get your hands on not to mention there is a large about of bullets and load data available for the 300 as compared to the 7.62×39. Just my two cents.

  6. Michael says:

    I wonder whether there is a practical difference between a subsonic ~220 grain 300 BLK and a subsonic ~230 grain .45 ACP. If they are traveling at around the same speed with the same weight at a distance that doesn’t significantly change that (such as 50 yards), how is 300 BLK better than .45? Obviously there are differences in the guns shooting them (AR vs pistol-caliber carbine), I’m more curious about the caliber itself.

  7. Ballistic6 says:

    I am not a “cartridge hater” per se, but I do agree with the assessment attributed to them. At the end of the day, the cartridge has done exactly what it was supposed to do… Make money for its corporate developers and proponents by wedging yet another un-needed caliber into a stupidly crowded market. There will always be the gear-queers, fanbois and caliber geeks who will buy whatever the new gee-whiz, cool toy they see in the glossy gun rags who make their money from ad dollars. As long as those guys exist, people will keep trotting out new (underwhelming) calibers and pimping them like they are gold.

  8. Cary Kieffer says:

    I’m looking forward to seeing what you think! Especially since I have gotten into suppressors. So far only 22’s but I intend to get more cans (from Barry) and I would assume a can for my 308’s would work with this cartridge too.

    I do have 2 simple questions maybe you will cover later…
    1. Does this cartridge fit in a regular AR mag?
    2. Will the suppressed loads cycle a regular AR rifle with no modifications for it?

    Thanks Mike looking forward to this series! Great topic.

    • Michael says:


      1) Yes. The cartridge is a 5.56/.223 cartridge that has been necked up and shortened with the same OAL as the 5.56/.223. This was done intentionally so the only change to existing AR’s would be swapping out the barrel.
      2) As far as I’ve seen, yes it will. There is still a significant amount of energy going down the barrel that AFAIK it will still cycle.

      If the price of 300 BLK ammo comes down significantly, I would seriously consider getting one myself.

    • Lonnie says:

      Yes the 300 will fit in standard AR mags and uses the same bolt as the .223/5.56. All parts are stock except for the barrel. You will need a 300 barrel and they are getting to be readily available.

  9. Mike Coker says:

    Cary, one goal of this series is simply my personal curiosity about the cartridge. There is so much hype over it. There were giant “BLACKOUT!!!” signs all over NRA Houston.

  10. Cary Kieffer says:

    I might be one of those cartridge haters to a certain extent but keeping an open mind I am interested to see the rest of this series. I don’t know diddly about this cartridge but I have heard it said that you can do anything the 300 can do with a properly loaded 7.62×39…Is this true?? Seems like if it is that the components would be easier to find. Just wondering? Thanks.

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