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According to its inventors at the Advanced Armament Corporation, 300 AAC Blackout is “full power 123-grain ammunition [for the AR platform] that matches the ballistics of the 7.62x39mm AK, with 37% more energy than 5.56mm M855, and 9% more than 6.8 SPC TAP 110.” In fact, “from a 9 inch barrel, the 300BLK has more muzzle energy than 5.56mm M855 from a 16 inch barrel. When 300 BLK is used in a 16 inch barrel, it has 23% more energy than 5.56mm M855 from a 16 inch barrel – with much higher-mass projectiles for a more dramatic effect on the target.” Or . . . “choose subsonic cartridges for optimal use with a sound suppressor – 220 grain Sierra OTM (open-tip match) bullets vastly outperforms a 9mm MP5-SD in penetration and long range accuracy.” There’s a lot more, but I partied pretty hard last night . . . Anyway, I like big and slow (e.g. Russian 9x39mm). Just sayin’.

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  1. Seems like a solution in search of a problem.

    6.8 SPC has better (terminal) ballistics, and more energy coming out of any civilian-legal barrel. Their documentation is full of propaganda and invalid comaprisons as well (TAP110 6.8 SPC–hollow points–to MC?) Now if they're going to price this stuff in the same range as 5.56 X 45, they might be onto something.

    • 308 diameter gives you a far larger bullet selection to choose from, plus brass can be made from 5.56. Mags can be used to full capacity. Uses standard 5.56 bolt face.

  2. Biggest benefits are that it uses reformed 223 brass, standard ar mags, and standard AR 556 bolts. It can't match 6.8 ballistics but does not need to. Its more potent than 223, efficient in shorter barrel, can ethically take deer with supersonic and run subsonic as quiet as an 9mm MP5 with superior ballistics and accuracy. I have ARs in 223, 6.8, and 308 but may well sell off my 6.8, mags, and brass in favor of the 300. I was thinking about 458 socom as a fun addition but this just makes more sense given full mags of 30, 220grain projectiles and parts comparability.

  3. The 300 Blackout’s best asset is the sub-sonic performance, along with just a barrel change to change the caliber. The 6.8, it’s has more ponies on top with super-sonic’s. I’ve been shooting 125 grain Ballistic tips through the 300 Blackout, and it works well on Coyotes and Jack Rabbits, and I plan to shoot a deer with it in the fall. In the range department, the 6.8 SPC would give me longer range, but I’m thinking of selling the 6.8 just due to ammo cost, and expensive Brass. It’s the darn Black rifle, they are fun to shoot, and who can just shoot a mag or 2 while at the range or in the great outdoors.

    The maker of the 300 Blackout, drew it up so it would be easy to make brass by forming and trimming down 223/5.56 brass. Once fired Military brass is plentyful, and is a good parent case for a 300 Blackout. I’ve been converting lots of Lake City brass, and there is no need to turn necks, I can form the brass, turn around and load it, then shoot it with out hassles. The case needs to be trimmed over 1/4 of an inch, which is a small hassle, but there are sources on the web to buy formed brass. sells brass.

    I’ll shoot up the rest of my 6.8 SPC, then I’ll sell the upper. I don’t have a mondo 458 SOCOM, but I might try the 358×39 from Delta Company Arms, then think about an above 40 cal. option for the AR platform. Got to love the black rifle and what it has become.

    • I am behind the times. I was looking at the Noveske website and saw the 300BLK; I have not heard of the 300 Blackout until today. I am wondering how you made out deer hunting with the Blackout, if you had the chance. I used my 223 this past fall and realize that something bigger would be better, I had been thinking 6.8. After reading your posting and seeing the obvious advantages my question is accuracy. How accurate is that round, what have you seen firsthand; what have you heard? What are it’s limitations?

  4. The 300 AAC Blackout is the 300 Whisper, 300-221 or 300 Fireball. The 300 Whisper name is owned by JD Jones at SSK Industries. The 300-221 and 300 Fireball names have been used by other manufactures to avoid paying royalities. Because it was not a SAMII cartridge chamber dimensions varied a little. This was not a problem for the hand loaders because most of them would cerosafe the chamber and manufacture brass for their rifle based on the dimensions they found. This will not work for mass produced ammo. I am glad they finally made it a SAMII standard cartridge. I built an AR 15 in this cartridge with a Noveske 16” barrel about a year ago. I also put a Gemtech Sandstorm on the muzzle. With 240 grain Sierra Match King bullets I get 5 shots in an inch at 100 yards. I think better is possible and I am still working on a more accurate subsonic load. I can ring the steel targets out to 500 yards with this as long as I range it carefully. Outlaw State makes some nice bullets for hunting with this cartridge, but I have not loaded any of them yet. The word is that they work great on deer. CH Tool and Die make a trim die for the Dillon power case trimmer. I ordered one today. I will be able to convert 223 to 300 AAC Blackout in one pass through the die.

  5. I agree with the majority here. I’m thinking of abandoning the 6.8. It’s certainly not as versatile as the 300 blackout, and I’m seeing that the 300 blackout is also cheaper to reload. It’s more difficult to find .277 vs .308 bullets, and if you’re willing to work for brass, the ability to use .223/ 5.56 cases is way better than paying the cost for 6.8 SPC brass or trying to find bulk bags at the quarterly gun show. I’ve also found that to get what I want out of a 6.8 AR, I have to build it myself; very little options. I see a greater push for the success of the 300 AAC Blackout than I did at the intro of the 6.8, which is confusing to me since Remington was one of the main proponents of both cartridges. I like both, but I feel that 6.8 lovers are a tiny minority in the black gun world, and it’s growing too difficult and expensive to continue supporting it as a “real-world” cartridge. Too bad.

  6. Put together an inexpensive 300 blackout using a DS Arms upper and New Frontier LW polymer lower with a change out to steel hammer and trigger. Out the door for $659. Can’t touch even a M&P Sporter or DPMS Oracle in 556 at that price here in CA with tax. Have about 300 rounds out of it, 99% handloads using a Harbour Freight mini cutoff saw and Lee dies and case trimmer set up for the 300. Limited to 25 yards at the local range, but able to do as well as my mini-14 both with an iron sights. Wife says its a little louder, but I don’t notice, but made sure to get a butt pad after bruising my shoulder on my first venture out. Fun little rifle my son can’t wait to get a chance to use it. He’s been off at college.

  7. 7.62/39 is perfect for deer, iI tryed the ranch rifle,shot militery bad and remington good, then iI bought a cz 550 ,it shot military good and rem. bad, military 39 ammo walked all over in a deer, zig zag, not what iI want to do with my food, rem. had good performance o deer ,just wish iI could have found factory round nose ,soft lead tip 135 grain, well anyhow 300 b.o. would and is my next gun, iI.ll make my own ammo at 1500 fps with 223 and that will be the end of it ,no 7.62/39 feed ,mag issues with AR, just get a barrel and full 223 gun or built from parts,the only thing iI can,t decide yet is barrel length and twist iI wish iI could find a barrel with 1/12 twist 14″ length with a supresser, for my teflon coted lead .308 135gr. molded wheel weight,loaded down to 1100 fps

  8. Hey Guys, Wow! So much raw data and good field notes plus after action reports on your many outings for deer, etc.
    OK, I’m thinking I want to play black rifle. This is new to me. A lot has changed since Basic at Ft. Benning. Not sure if I’ll build or buy, but I’d like to birth a new AR/M4, 3 position lower for “Select Fire” and drop in a binary or Echo-Trigger.
    Help me here, though, please. .300 Blackout.
    Why is it called “Blackout”? If the primary use
    Is a defensive one, what is recommended as
    a home defense round for an AR./M4 setup with a laser? The plain ol’ white bread .223/5.56? See in home defense, I like the flat out stopping power of the hollowpoint .45 ACP cartridge in a pistol. There’a a lot of SLAM, but not so much continual travel momentum through walls. A critical consideration in home defense, with a family situation.
    Ok guys. Thanks for any good experienced advice.

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