.300 AAC BLACKOUT (.300 BLK / 7.62x35mm)

This week there was an interesting development from Advanced Armament Corp. The company has introduced the .300 AAC BLACKOUT cartridge (otherwise know as the .300 BLK or 7.62x35mm) along with a short-barreled AR-15 upper receiver and suppressor chambered in it.

Remington Seven rifle chambered in the 300 AAC BLACKOUT

The cartridge has been designed to duplicate the 7.62x39mm ballistics in a cartridge designed to work well in the AR-15 platform. Unlike the 7.62×39, the .300 BLK does not have an extreme taper. The taper of the 7.62x39mm, and many archaic but still popular dangerous game cartridges such as the .375 H&H Magnum, has often been cited as an advantage because it allows the cartridge to feed and extract easily. According to AAC, the AR-15 platform was not designed to handle an extreme tapered cartridge, and instead of increasing reliability it decreases it.

.300 BLK Loads, 5.56mm NATO (bottom)

The concept of a modern 7.62x39mm cartridge is not new. The .300 Whisper, which was introduced during the 1990s, is similar both in concept and ballistics. The Whisper has a moderate following but never achieved widespread adoption. I cannot think of a major manufacture who currently manufactures rifles chambered in the Whisper. The reason for this is, I would guess, the same as why we are currently seeing the demise fragmentation of the 6.5mm Grendel concept: licensing costs.


The 300 AAC BLACKOUT PDW upper receiver is compatible with all AR-15 lowers. It has a 9″ barrel and so is legally a SBR (Short Barreled Rifle). When combined with the AAC 762-SDN-6 suppressor it makes less noise than the 9mm MP5-SD while providing better ballistics and energy.

AAC 762-SDN-6
300 BLK

I sincerely hope The Freedom Group (AAC, Remington, Bushmaster et al.) promote widespread adoption of this cartridge. The concept is great for military use, self defense and hunting.

[ Thanks to Robert, Fred and Matt who emailed me about the new cartridge. ]

UPDATE: Jason of AAC commented …

First the 300BLK in 3 flavors (123gr, 155gr, 220gr) has been submitted to SAAMI and is a completely open standard. No licensing fees at all, anyone is allowed to use it. Reamers, dies, etc should be easily available, as well as ammo made by other manufacturers.

Second, this was not designed as only a suppressed system, it was designed to allow .30 cal use in an AR system primarily- while keeping as much of the weapon system standard as possible, and allowing full-capacity standard magazine use. The smaller powder charge and the larger projectile does allow for very effective suppression, but the ballistics really shine on the supersonic ammo.

I hope other ammunition and firearm manufactures get on board.

UPDATE 2: It is worth pointing out that the .300 BLK concept is completely different from the .30 Remington AR concept. The .30 RAR concept is better compared to the 6.8mm SPC. Also, it is designed for hunting rifles, not military carbines.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Nick

    Looks like a “(re)branded” .300 Fireball cartridge… yep. .223 casings are easily adapted for handloads. Cool round for sure, wouldn’t mind playing with one of these sometime. Noveske had some .300 fireball barrels for sale recently, the chambering is not all that uncommon.

  • iMick

    Ok I’m totally caught up in the FUD. WANT. New calibre would answer so many questions. Logistics Schmistics. Just do it already!! 🙂

  • snmp

    Like .300 Whisper (also known as .300 Fireball) and the HK 7,62×37 (for the HK SL9SD) by Royal Ordonnance. That’s cheaper and simpler to take weapon in 7,62×39 M43 with silencer.

    Why note in the same way of Russian 9×39 (in fact 9,3×39) make a clone for AR15 platform.


  • Steve, I really would appreciate any insight of 6.5 grendel’s demise. Do you think that it is really impossible for it to achieve popularity, or to be adopted by any military force?

    If it is the case, I believe that it is a pity. Specs and ballistics of grendel would be close to ideal for a Universal Rifle (from CQB to Marksman) and SAW.

    Thanks in advance and excuse me for my offtopic question


    • Yes, I concede demise may have been to strong a word. “Fragmentation” is a better word.

      Juan, I think it has no hope of ever being adopted by the military.

  • Vak


    I guess they should make a ACR upper for it, seeing how it’s popular


    Great concept, but it’s going to fail like a lot of other proprietary cartrdiges. Maybe (emphasize on maybe) it could get some moderate sucess if it manages to get some military contract or something alike, but seeing it’s a cartridge made for suppressed weapons (and apparently, gun owners who also own suppressors are a minority in the US) and/or SBRs (again, Title 2 and all that) its future doesn’t look pretty.

    (now where is my 9×39 saiga, izmasch ?)

    • 9×39mm is a nifty concept, and I would love to own one, but unlike the 7.62×39 or 300 BLK, it would not be suitable in a supersonic intermediate range role. The ballistics would be terrible. The beauty of a 7.62 cartridge is that you can use subsonic when appropriate and longer range and more powerful supersonic when needed.

  • Bert

    How did you get the idea that it is only for suppressed weapons? That is like saying 9mm is for suppressed weapons just because it is good for that use.

    This cartridge is great for hunting with the AR – it shoots 30 cal bullets at AK ballistics. Hunting is not legal with 223 in many states.

  • Sian

    Less noise than the MP5SD 9×19? That’s fairly impressive if true.

    And I gotta echo Vak here, if we’re talking about rounds made for suppressed weapons I would like to see some 9×39 platforms out there and see how they perform.

  • pro

    ballistics charts please…………………

    small cartridge , less pouder , 6.8 SPC class power , needs only new barrell , made for LE/special ops units

    AMMO for multi purpose use(123gr) cqb (155gr) cqb-suppressed(220gr)

    same ammo count , only a 1,5 pound more weight than 5.56X45 per 300rounds (my estimation).

    I see a winer .

    I also see a 6.5mm variant that achieves grendel ballistics and beets the crap out of the 7.62X51 out to 1000yards

    Finaly i see that with standard technology the weight goals of CTA could be achieved without the gazillion dollars in R&D .

  • Couple of comments,
    First the 300BLK in 3 flavors (123gr, 155gr, 220gr) has been submitted to SAAMI and is a completely open standard. No licensing fees at all, anyone is allowed to use it. Reamers, dies, etc should be easily available, as well as ammo made by other manufacturers.

    Second, this was not designed as only a suppressed system, it was designed to allow .30 cal use in an AR system primarily- while keeping as much of the weapon system standard as possible, and allowing full-capacity standard magazine use. The smaller powder charge and the larger projectile does allow for very effective suppression, but the ballistics really shine on the supersonic ammo.

    • JasonAAC, thanks for the comment.

  • Other Steve

    Most guys just do NOT get this. This isn’t a proprietary cartridge! What aac did was take the Whisper / 300-221 and legitimize it by getting it saami tested and approved. This means it has actual numbers associated to the size and pressures now, this means anyone can build guns in 7.62×35 or even 300 Blackout. It’s the complete opposite or proprietary!

    Whisper (and grendle) will never take off because both owners want to get rich off it. AAC doesn’t get a dime if FN for instance makes a SCAR in 300BLK, what they do get is the very first products on thr market for it (silencers and ammo) from day1, a huge advantage. They also get to be the most respected company for that round because they did the the testing and development. Are you likely to buy a suppressor for it from some company that offers a 30cal generic or aac who makes cans for that round they developed?

    This is a big deal for anyone even mildly interested in silencers, whisper, or a more powerful AR. Not exactly about AAC alone.

  • aczarnowski

    As a 6.5 Grendel owner, I can say it is not perfect in AR platforms because:

    – The cartridge taper really does cause problems in the magazine
    – Magazines are even more finicky because the fat cartridge body wants more space in the mag well leaving you with a thin, flexible mag
    – The expanded bolt face leaves precious little metal for the lugs

    All the claims AAC is making as advantages for cartridges based on the 5.56×45 case like 300BLK match my experience with my Grendel. The AR really doesn’t like tapered cartridges.

    I’m watching this one closely. I don’t live in a “long shot” area so 6.5’s range advantage doesn’t come into play for me. Maybe Les Bear’s 264LBC will drive solutions to some of the mag issues, but after I use up what little 6.5 Grendel ammo I have left I’m going to be looking for other options because I can. One that uses 5.56 mags and bolts, unlike 6.8SPC, would be a pretty easy migration.

  • Will Atwood

    Makes no sense to me. As a geezer I always thought the 5.56 was a regressive cartridge for military use, and far inferior to the .308 as a military round. Shot some of the early M-16’s in boot-camp and was nonplussed. This round duplicates essentially the ballistics of the old AK round and is therefore a lessor 30-30 WCF duplicate at best.

    If the 30-30 is limited to short range use on deer, and it is judged to be a 150yard proposition at best, than this round is also limited as a hunting round too. Even a boattail spitzer bullet won’t help that a great deal.

    Deer are relatively light boned critters and so are people. Why will this thing shoot an enemy soldier farther than it will kill a deer?

    Seems more logical to teach soldiers to shoot and give them a weapon that will reach out further, and have a flat enough trajectory to make longer hits more probable and retain enough downrange energy to be effective.

  • kvalseth

    Really an ideal cartridge for the Magpul PDR.

  • emdfl

    Why not go back to the Thompson .223TCU? .223 necked up to 7mm. Wide selection of projectiles, feeds from a standard mag, and with modern powders, velocity should be respectable; or the 6.5X.223, same arguments.

  • Tom

    Please explain why you said.. we are currently seeing the dimise of the 6.5 Grendel cartridge ??? I would disagree with that.. More manufactures then ever are chambering for this cartridge.. Hornady just started producing factory ammo, brass, bullets for the Grendel.. The Grendel was held back in the beginning because because demand always exceded supply.. Ammo, brass was hard to get and expensive.. Now there are lower cost options available..

    I would also like an explanation why AAC said the AR15 was less reliable with a tapered cartridge.. That doesn`t make sense to me.. Our military has rejected new cartridge designs because they did not have enough taper for reliable feeding and extraction for military use..

    • Tom, there has been a lot of controversy regarding the Grendel. The companies licensing terms are not good and firearms, barrels and ammunition is sold under many different names and slightly different cartridge or chamber dimensions. The concept is by no means dead. Hopefully the .264 LBC (both in name and chamber dimensions) will be widely adopted:


  • I think the facts that it uses standard mags with no loss in capacity and only requires a barrel/gas tube swap (uses standard 5.56 bolt!) place it squarely ahead of the other short .30 cal options out there (.308+/AR10 is a whole other group to me.)

  • Jim

    @iMick “Ok I’m totally caught up in the FUD”

    FUD stands for fear, uncertainty and doubt; it’s not a synonym for hype. Just FYI.

  • Vitor

    The 220 grain one seems very cool. Plenty of penetration due to the sectional density even at low speed, and of course the quite high BC.

  • Ladyfox

    *reads thru the article and thinks for a moment…*

    Well, my question is can the Enfield be re-chambered for it? -_^

    who still wants an Enfield, with a working detachable mag, in 7.62×39, 5.45×39, and 5.56×45 *drool*

  • Bill

    “demise of the Grendel”? based on licensing costs?

    Hmmm….Hornady just started loading for it, more manufacturers are signing on all the time to build it, and there is at least one more major ammunition manufacturer who is in negotiations to build ammunition.

    To top that off, David Fortier has said that there is at least one more major manufacturer who is about to release a new rifle based on the Grendel cartridge.

    Me thinks thou doest jump the gun!!!

  • Ric

    This will be an interesting round if it 1) Makes it to market and 2) becomes available in a low cost loading that regular guys can afford to practice with.

    I like the idea of a .30, 7.62×39 mm class round in a package that will run in the same mags in an AR-15 but the cost of ownership has to be close to the 7.62×39 or it will be DOA, IMHO.

    Also, I wonder how this compares to the .30 Rem AR round that came out in 2008. I know that the .30 AR is designed for hunting so I would imagine that it packs quite a punch. Do we need another .30 round for hunting?

  • charles222

    I can see the suppressed variant being quite dandy. The rest-meh.

    Also, I’m fairly certain Thompson-Center makes barrels for the Contender in .300 Whisper.

  • Lance

    Looks cool so Steve you think SOCOM will replace the MP-5 SD series with it?? I doubt it because in maritime ops the rile round will ricochet, inside a ship a 9mm round wont go as fast, less dangerous.

    But in outside ops yes I think this is alot better.

  • Timothy

    I think this is pretty darn cool if the ballistics info is accurate, and it has a shot now that AAC is part of Freedom Group.

  • Bill

    The Grendel licensing terms are fairly non-problematic. I think its funny that people who have never talked with anyone who is a licensed Grendel manufacturer make a big deal out of it.

    Go ask someone who is licensed how big a deal it is! I have, 3 different licensees have told me it adds less than 2% to the cost of the rifle. Thats not exactly a deal breaker.

    As for SAAMI, I suspect that we will see SAAMI certification of the Grendel, (and not one of the variants) within the next 2 cycles of meetings. Remember, as I understand it, you have to be a member of SAAMI to submit, and Hornady is, and now makes the ammo, which seems like a sure bet that they will submit, (or maybe have already.)

    The Grendel has no feed problems in an AR due to taper, the mags have had their difficulties, but it is strictly a mag issue, not a cartridge issue.

    There are new mags very close to market, and CProducts is working diligently to solve their magazine problems. Its not a design issue, its a QC issue. Remember it was 20 years or more before 5.56 mags were reliable, and some people say they weren’t REALLY reliable until MagPul!

    I applaud new cartridge designs, and I hope new cartridge works, but it does seem to be an infringement on the Whisper!

  • Tmash

    This looks promising. But im kinda intrested in its wound ballistics and how it does out of a short barrel. i want something bigger in my M4 so bad. Apparently the Armys holding a competition to replace the M4(source is the Army times). and the article did state that it didnt have to be 5.56 or 7.62 nato (but the appliacnt must provide own ammo if its not) I wonder how a piston driven 7.62x35mm would do in the competition.

  • Tom

    Part of the Grendel licensing agreement is to hold to high levels of quality in the product manufacture. That`s the most important part of the whole agreement.. and why Bill Alexander did what he did.. Les Baer discovered only the Grendel name is patented.. Not the cartridge itself.. His .264 LBC is the same as the Grendel.. He only slighty changed the chamber throat and lead angle dimensions to avoid any possible lawsuit.. I have been a Grendel owner for 4 years.. The popularity is growing everyday.. Guns, barrels, ammo, brass has always been in short suppy.. due to the fact demand exceeds supply.. Bill Alexander himself said he never thought it was going to be as popular as it is.. it has exceeded his wildest dreams.. More and more manufacters are jumping on the band wagon, because this product is selling.. there is a demand for it..


    • Guys, I did not mean to bash the Grendel. I like the concept. Lets please keep this discussion about the .300 BLK.

  • Bill

    Steve, sorry! It just confuses the heck out of new buyers when they see a respected site like this one make those kinds of comments about the Grendel. You have a huge readership, and LOTS of blogs link to yours so your impact is huge.

    My wonder about this new cartridge is what is its advantage over the Whisper? Simply that they are going to go SAAMI?

    The Whisper IS widely available, and the brass doesn’t seem to be tough to make. Having factory brass is cool, though, as many have found.

    I like AAC, and wish them well with this!


  • Lance

    The army fixed the copmetition for 5.56mm any way unless compaines pay for ther own ammo. I doubt 7.62×35 will be included.

    Most dont think the competition will go far.

  • snmp

    For the same pupose 3 calibers for have same baltistic of the 7,62X39 M43 in AR15 (SANTAG mag)

    * .300 Whipser (7,62×35)
    * HK 7,62x37mm (for SL9SD) by Royal Ordonance
    * .300 AAC BLACKOUT (7,62×35)

    But Russian have move to 9x39mm (9,2 bullet) for have more baltsic impact with low velocity

  • root man
    • root, a subsonic 6.5mm projectile would be much less powerful than a .30. Also, a lower powered cartridge (eg 5.56 / 7.62×39 / .300 BLK) is more controllable as full auto.

  • 6.8 had SAMMI and Remington behind it, and it’s not supplanting 5.56.

    AAC is owned by the same folks as Remington, and since Rem routinely messes up introducing new rounds…

  • root man

    Cool just neck it down the proper 6.5 for a good bc and be done!

  • Back to address a few issues as i can:

    Tom- “I would also like an explanation why AAC said the AR15 was less reliable with a tapered cartridge.. That doesn`t make sense to me.. Our military has rejected new cartridge designs because they did not have enough taper for reliable feeding and extraction for military use..”

    Less- reliable in terms of feeding from the magazine – with the design of the magazine and the magwell, the AR needs a fairly straight ammo stack to feed well.

    @Ric- “This will be an interesting round if it 1) Makes it to market and 2) becomes available in a low cost loading that regular guys can afford to practice with.”

    1. It will be on the market, Remington is currently running 100,000 rounds with full production planned for the first of the year.
    2. The goal is to have this priced with 5.56… different grades from plinking to hunting to military.

    @Lance- “… inside a ship a 9mm round wont go as fast, less dangerous.”

    The subsonic velocity of the 300BLK 220gr is about the same as the 115gr MP5-SD 9mm… better in every way for putting down bad guys.

    @Bill- when it comes to licensing, and adoption of a cartridge/weapon system ANY licensing arrangements or costs hamper the development and spread.

    @TMash- “But im kinda intrested in its wound ballistics and how it does out of a short barrel. i want something bigger in my M4 so bad.”

    Part of it’s primary design was for good ballistic performance out of a short barrel (unlike 5.56).

    @Bill- “My wonder about this new cartridge is what is its advantage over the Whisper?”

    Mainly reliable function in ARs. Open specs. Factory brass.
    more later

  • The other point of this over 6.8 or 6.5 is the use of 5.56 standard mags, bolts, carriers, etc, etc… everything really except the barrel.

  • TCBA_Joe

    Jason, I’ve been following this on several blogs and forums since it was announed the other day. It looks awesome, your team did a great job. The release was epic, I don’t think you could have done better announcing this product, especially with uppers for sale within a couple weeks.

    What I didn’t realize was the pricing structure making it close to 5.56. If Hornady comes out with steel cased training ammo in the same price range, it’s a deal sealer.

  • pro

    Complete ballistics charts with velocity and wind deflection per 25-50 yards please .
    Is this a close combat cartridge? How it compares to 62-77 grains 5.56X45 cartridges between 150-500 yards?

    Complete ballistics charts please……………

  • Redchrome

    For those who want one in smaller bore diameters, consider Knight’s Armament’s 6×35 cartridge. Pretty much the same case, but in a smaller bore size. It’s designed for SBRs and not as powerful as even the 5.56×45 when shot out of a longer barrel.

    Thanks to JasonAAC for clarifying why the AR15 isn’t reliable with heavily-tapered cartridges. Also to aczarnowski for his experience with the Grendel. It really comes down to the broken-by-design AR15 magwell that has constrained fighting cartridge development for so many years in this country.

    The .223/5.56 case can be necked up to .338 caliber as a maximum, but it becomes a straightwall at that point, which isn’t good for feed reliability. .30 caliber is a fine size, there’s a bajillion bullets out there for it.

    9×39 is pretty much the same thing as this, just a few mm larger because it has a bigger head diameter. (11.35mm head as opposed to 9.6mm). Not sure what would be wrong with a supersonic load for 9×39; the bullet would be stubby, but so would a 123gr bullet in 7.62×35.

  • charles222

    I see SCAR/ACR hinting with that last post, JasonAAC. :p

  • Tom

    The 300 Whisper never caught on.. except for a very small niche market.. The 300 BLK wont do any better.. Very few new cartridges catch on.. Dispite all the marketing hype.. Look at all the new cartridges that were introduced by Remington and Winchester, and other companies over the years.. There mostly failures.. If you can`t get a large military contract with the 300 BLK.. it will be a failure also.. Our military wants to stick with established NATO cartridges..

  • Steve: In their September 1993 issue, Guns & Ammo ran an article regarding a 9x39mm wildcat conversion of the Ruger Mini-30. The .350 x39mm cartridge from a 18.5″ barrel gave equivalent velocities to .35 Remington factory loads from a 20″ barrel. A 180gr spire point at 2,200 fps or 200gr spire point at 2,075 fps would be nothing to sneeze at.

  • Cymond

    Ok, I gave the 300 Blackout some thought. I’ve been considering bigger-than-223 uppers for a while, and the 300 BLK is the first AR cartridge (that I know of) that gives me a bigger bullet without sacrificing capacity. I WILL build myself an AR upper in 300 BLK if AAC & Remington manage the following:
    *reasonable price
    *needs only a barrel swap for an AR-15
    *AR-15 barrels are available (barrels, not just full uppers)
    *no 6.8-esque issues from Remington

    • Cymond, it only needs a barrel swap. I am sure that a variety of companies will offer barrels.

  • Jeff M

    I’ve always wondered why I can’t get a 7.62×39 ar-15, does anybody know the answer to that question?

    Seems like an ar-15 chambered for 7.62×39 that accepted AK mags would be great. I don’t like the rear sight on the AK, or the sheet metal for that matter.

    Even if I needed custom mags it’d still be better than a brand new cartridge, the 7.62×39 ammo is so cheap…

  • Redchrome

    @Jeff M,
    google ‘AR-47’ and you’ll find some links and images.


    Also look at MGI’s MARCK-15.

    The MGI lower is expensive, but reputedly works. I’ve handled one in the store, and while I don’t think it has the best latching mechanism in the world; it should work acceptably well. (Part of the reason for Kalashnikov reliability is the way the magazine latch works – a swinging lever mating with a tapered lug gives lots of dimensional tolerance and a tight lockup under many circumstances).

    There are AR-15 uppers available all over the place; however they’re intended for use with the AR-15 style mags like Cproducts makes:

    which are flimsy compared to an AK mag. So the upper may need to be modified a bit to work with AK mags. (Involves a milling machine and a ball-end mill; I think there are directions on the AR-47 website). The MGI Hydra upper should not have to be modified to work tho since it was designed to work with that lower.

    I’ve thought for a while that given an Adams Arms piston kit, and an American Spirit Arms side-charging-handle upper reciever, you could have a pretty decent rifle.

    Or you could just go buy a Robinson XCR, which is much the same thing only more heavily built — but lacks the heavy-duty AK mag. 🙁

    The perfect rifle has not yet been built. 🙁

  • Ladyfox

    Jeff M,

    I think the reason why the 7.62×39 has been a bit rare is due to the magazine issues. My guess is that based upon the other comments here that the taper of the round is most likely the primary cause as to the magazine issues. Myself, I’d love to have a 7.62×39 upper but from the looks of things until someone solves the magazine problem it’s really not going to happen. -_-

    As far as the .300 AAC I’d really like to see it in other platforms beside the AR since it looks like it would go well with the Scout rifle concept.

  • Ladyfox

    Oh, one thing I forgot to mention in my previous comment as well is that this would also be a good basis for a magazine-fed bolt-action rifle that would be able to share magazines with the AR. Mods, if you can add this to my previous comment I’d appreciate it since I do not wish to spam here. ^_^

  • Bill


    The AR mag well is straight, and the 7.62×39 is very tapered. The cartridge feeds best from a banana shaped mag, and so that straight mag well presents problems. Many have tried, but making mags that feed consistently has been an issue.

    There ARE several manufacturers who build 7.62×39 uppers, as well as 5.45×39 uppers, and 5.45 is even cheaper than 7.62!!


  • “Cymond – I WILL build myself an AR upper in 300 BLK if AAC & Remington manage the following:
    *reasonable price
    *needs only a barrel swap for an AR-15
    *AR-15 barrels are available (barrels, not just full uppers)
    *no 6.8-esque issues from Remington”

    I agree on these points:

    1. Ammo prices from Remington should be in line with their 5.56 SKUs. Anyone else is free to make the ammo and we have been talking to other manufacturers to fill additional end uses like hunting/etc.

    2. Yes, the conversion ONLY requires a barrel swap

    3. They (barrels) will be available from us as 9″ and 16″, Noveske has announced that he will be making 300 BLK barrels/uppers in various lengths.

    4. I hope not too. So far, so good.

  • Christian

    Are there plans for Remington to start manufacturing rifles with this cartridge?

  • charles222

    Not to mention more ballistically effective. Which is why the Russians adopted 5.45 in the first place and have kept it in use for going on 40 years now.

    I guess I’m just never gonna get the love for a round that duplicates .30-30 Winchester ballistics and is typically found in crudely made, overly heavy rifles with bad sights and the max effective range of a 9mm submachine gun… :p

  • Rijoenpial

    Hello there guys,

    I think the major problem for these intermediate calibers, such as the 6.8 SPC, 6.5 Grendel and, of course, the theme of the debate here, the 7.62×35, is:

    You guessed it, NATO!!

    All these intermediate calibers offer various advantages over the two major ones, the 5.56×45 and 7.62×51, but the fact is that the US Military must abide by NATO rules regarding calibers, as well as the Geneva Convention, among others!

    These calibers can only be used domestically, for hunting or target practice, and not overseas!

    So, unless some serious lobbying is undertaken on NATO, these calibers, no matter how better they are regarding the major ones in terms of stopping power (5.56’s major flaw) or travel distances and second-shot targetting (7.62’s major prob), they must be adopted by NATO first before being issued to the USSOCOM forces and Regular Military ones!

    Until such time happens (it could take many years), the US forces are stuck to having to fight overseas with those flawed calibers! Domestically, they could, but we all know that the true customers of any weapon manufacturer are the military ones!

    I mean, the SCAR has the ability to use 6.8, having had a prototype that fired them, and they dropped it entirely! I mean, nowhere in any flyer or promo regarding the SCAR was this ever addressed, only the multi-barrel capability!

    Of course, covert ops can use them! I am not that naive! But any regular, legit op overseas by the US Mil has to abide by NATO rules! That is the rule!


  • Matt

    I really like the concept of this caliber. Jason thank you for our replies. It is good to seem companies like AAC recognizing the importance of blogs like this and commenting.

    If you do manage to get the prices competitive with 5.56 I will make this caliber a definite edition to my collection In an suppressed sbr format.

    Question- if you are free to talk about it is, what are the theoretical shortest optimal barrel lengths for this cartridge before you start losing too much power? It the round being designed with fast powders for SBRs as primary use?

  • charles222

    Rijoenpail: You’re wrong. SOCOM can roll with pretty much whatever it feels like, NATO-approved or not. They can even ignore the Barry Law if they so desire.

    7.62×35 is a highly specialized round (frankly, the only one I see of being of significant tactical value is that beast of a subsonic round, but that’s another story) that’s going to see a niche market, probably based around it’s subsonic chambering. The reason SOCOM uses the 7.62mm and 5.56mm in the SCAR is because they fill their tactical niches exceptionally well.

    7.62mm NATO is the real 6.8-killer, though; 6.8 can throw a heavier bullet further than 5.56 can. Sure, great, awesome. 7.62mm NATO can throw a heavier bullet further than 6.8mm can, and also “drop down” to 6.8mm-level loadings, if you so desire; additionally, the sheer number of countries that have issued the FAL/G-3/etc practically guarantee that 7.62mm NATO will be available if you need it, and national militaries that SF may be working with will be familiar with it and have it on-hand.

    5.56mm NATO is also fundamentally widely available and versatile-over 80 countries have adopted the M-16 and/or 5.56mm ammunition. Similarly, the SF-specific loads for it-the Mk 262 77-grain HPBT and 62-grain SOST round-are superb out of a 14 to 18 inch barrel. If SF had an issue with it, they’d replace it with something else, like how the USMC and Delta issue 1911 .45s, despite that weapon and it’s chambering not being a NATO standard by any stretch of the imagination.

  • Does this mean I just spent a boat load of money building my dream whisper, and now it won’t make sense because the 300BLK will do the same, but with mass produced ammo?

    Sad. Please tell me the ammo is swappable!

  • Rijoenpial-

    With all due respect, NATO has no say on what ammo our soldiers can use, especially our special operations ones (all branches).

    The Geneva convention has nothing to do with expanding ammo, it is the Hague convention, and the US never signed on to that. It specifically bans ‘dum dum’ bullets or bullets that are considered to cause “unnecessary pain and suffering”… these subsonic 300 BLK rounds are not hollow-point rounds as those are defined, these are OTM bullets where the tip is a result of manufacturing and not a design feature.

    (As a side note, these “rules” only govern warfare against a recognized state’s army… our current adversaries do not fit this definition.)

    The various US Mil JAGs have all ruled that the OTM rounds are legal for use by the US Mil anywhere. For example the M118LR and MK319 7.62 and the MK262 and recently the MK318 5.56 rounds. These are now fielded by all the Marines and many of the Army units in AFG.

  • Matt-

    Thanks! As for barrel length, we settled on 9″ and 16″ for our two initial offerings. They are both 1:8″ twist. We have tested down to 8″ and up to 20″ and everything in between. I personally wouldn’t go below 8″ because that 220 gr. subsonic is a LONG bullet and you want to make sure it is stabilized.

    Likewise, you have diminishing returns with a long barrel as the powder is fast burning (and there is not a lot of it). The big upshot of this is you get minimal muzzle blast even in very SBRs.

  • charles222

    So, since there’s an AAC guy here…

    -What sort of range would I be getting with this out of a 9-inch barrel, specifically the 220-grain round? I’m assuming 2-300 meters-is that accurate?

  • Tom
  • Tom

    300 Whisper Forums with some 300 BLK info


  • Redchrome

    Thanks much to JasonAAC and Tom for the helpful links and information!

  • Matt

    (As a side note, these “rules” only govern warfare against a recognized state’s army… our current adversaries do not fit this definition.)

    Thank you for posting that Jason. I get so tired of these “Geneva convention” nonsense arguments against expanding ammo.

    That stupid agreement was written back when no-one new anything about hollow points. They were brand new. Hell there are still idiots walking around who think hollow points are ment to cause suffering.

    I would rather “suffer” a quick death from a hollow point than a slow one from a FMJ gutshot.

  • Delta Company Arms, LLC is offering .300 Blackout custom AR uppers that are built exactly to customer specs at surprising prices. Garunteed MOA.
    The website is under construction but there is some info available.

  • We will also offer complete, headspaced barrels with extension for around $250USD.

  • Bert

    Colt and others have made 762×39 AR15s, but the bolts break and the magazines cannot physically work due to the straight shape of the AR magwell.

  • Tim

    I retired as a Swat Commander several years ago and started building AR platforms as a hobby, and the Obama scare. I always thought the AR M4 platform needed heavier bullets. The 7.62 is great, but just to heavy in weight. Both the rifle and the ammo.

    I buildt my 300/221 Fireball several years ago. I got a Noveske 10 1/2 inch barrel and put together an AR Pistol with the purpose of using subsonic 220 gr. bullet. I also got the Gemtech Sandstorm suppressor.

    The gun surpassed my expectations. It is crazy accurrate to 100 yards. I handload since factory ammo wasn’t available. I’ve never experienced ANY malfuntions other than when I tried using PMag mags.

    I then turned my attention to a heavier bullet, longer range, AR. I choose the 6.5 Grendel. I again handloaded 120 gr. bullets since factory ammo was so difficult to find. Again, accurracy has been outstanding, and again no feeding issues. I use the CProducts mags.

    My 6.5 Grendel using 120 gr. Sierra tracks almost identically with my 175gr. 7.62 rounds out to 1000 yards. For a combat rifle round, the 6.5 Grendel shoots out further, and hits harder at all ranges, than the 5.56 rounds, AND reaches out to 1000 yards like the 7.62, BUT is a heck of a lot easier to carry around than the 7.62 with 200 rds of ammo.

    I think I have the best of both worlds with my CQB 300/221 FB (300 BLK), and my 6.5 Grendel. Hopefully more major manufactures will come out with factory ammo and mags. Maybe for the first time in my life I was ahead of the curve on something.

  • The 300 Blackout is a fun round, I’m shooting Super sonics and most of my loads are 125 gr Ballistic tips. It works fine on Coyotes, and it WILL take down a Utah Jack rabbit.

    I hear Remington brass will be coming soon, but in the mean time, I’m making plenty of 300 Blackout brass, and sell it at


    Aaron at http://www.DeltaCompanyArms make a nice barrel in 300 BLK too.

  • AAC and Remington did a big favor to a lot of us by standardizing a 221/300 fireball round. I can’t wait to test some of Remington’s ammo offerings, but it’s still slow coming.

    In the mean time, handloaders can test loads with brass formed from 5.56 cases. It was a huge plus that the blackout doesn’t have any neck thickness problems with converted brass.

    I’ve been loading 125gr, 145gr , and soon I’ll try some 175 gr loads to see if I can make major for USPSA 3 gun shooting.

    If you don’t want to make your own brass, several people are offering Brass for sale. Good news is also out that Remington factory brass might be out within the next 1-4 months. MidwayUSA might be the first to offer the brass, sold in 2000 piece lots.

    The Blackout isn’t a hotrod speedy wildcat, but for predators, it’s not lacking.

  • Dan

    How about at 20″ barrel? would we go over 2,500 fps with a 123 gr bullet? I think this would be a nice coyote cartridge.

  • Redchrome

    if you don’t mind the overall length getting a bit long (or alternatively, want the really cool long-barrel look); there are custom makers that will make you a 24″ bbl. I doubt you’ll get *that* much more speed out of it; but you’ll be able to get some pretty good speeds.

    • mike

      Hey i just bought the AAC .300 blackout upper, and put a dpms lower on it. i shot the gun today and it would not feed any of the rounds after the first shot. I had to manually pull the action back each shot. Have any ideas on the problem?

      • Dan Hermann

        I have been thru this myself. Check the gas port hole on the barrel. Many of the barrels made have too small a gas port hole. I had to open mine up to 0.110 inch to get enough gas to cycle the action.
        I am working on a gas piston kit now to get that to work as well. Looks like it also has this problem, designed for the .223 the gas block hole is too small. I opened it up and it now cycles the light bullets ok. Still working on that one though. Check the .300blk forum.

        As far as mag functioning the bullet can’t be seated out to far or the ogive will hit the magazine rib inside.

      • Ed

        Mike, did you ever resolve your .300 blk feeding issue? I just shot mine for the first time today and had the exact same issue. I have an H2 buffer and was thinking I may need to go with a lighter one. Thanks.

      • Dan Hermann

        My .300 is up and running nicely. I have gotten the bugs out of the gas piston kit. It had the same problem, too small a hole for the gas to come thru. I also added a light recoil spring (for 9mm). Check out the .300 forum for more info.

  • Bob Esposito

    What I find most interesting is how it seems we’ve basically come almost full circle to the German 7.92×33 Kurz used in, granddaddy of all assault rifles, the StG 44. A 125 grain projectile at 2250 fps from a 16.5″ barrel. I believe the Blackout is a significant improvement over the Kurz, especially with the incorporation of a reliably cycling subsonic round. What more could you ask for in a handy and light weight package? I believe once the naysayers get there think on, and realize what the Blackout is all about, it will prove to be an outstanding success. I bought my first rifle in Blackout from Noveske in the fall of 2010 and haven’t looked back. I’ve used it in local defensive carbine matches loaded with 147 grain fmj’s, around 2000 fps, and suppressed 220 grain subsonic rounds (too much fun), and have had excellent results. I’ve also begun experimenting at long range, 400 to 600 meters, with the H-59 reticle in my S&B 3-20×50 using both super and subsonic loads achieving excellent results. Now, with the advent of the outstanding Barnes X bullet, with an ogive specifically designed for this cartridge, I’ll be hunting deer with it this fall. WHAT A DEAL!!!