State Your Case: 300 Blackout vs. 5.56mm NATO/.223 Remington
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State Your Case: 300 Blackout vs. 5.56mm NATO/.223 Remington

This article proved tougher to write than the other articles I’ve written so far in my State Your Case series. Many of the arguments that I found worked for the others didn’t quite work here. Today we’re taking a look at two rounds for the AR-15 platform that have been in quite the rivalry in recent years with no end in sight: the .300 Blackout and .223/5.56mm.

To begin, we’re going to consider this a discussion on the AR-platform. There are bolt actions, single-shots, full-auto, and even pump actions made to chamber these cartridges, but the vast majority of people shoot them in an AR-15.

The real benefits of both rounds come from the AR platform, but that isn’t to say that the others are bad choices. As an example, I think that it’s unfair to give the .300 BLK points because it’s virtually silent in a suppressed bolt action firing subsonic ammo and say that the .223 is bad by comparison because it’s louder.

Side-by-side, the two cartridges share a great deal and a somewhat common lineage. .300 BLK is dimensionally similar in taper and case geometry to the .223, which is essentially its parent case. Brass for the .300 BLK can be formed from cut-down .223 cases. As a result of this, the only difference between .300 and .223 rifles is their chamber and bore. They share literally every other part, including magazines and bolts.

The reason that the .300 BLK is so successful is because it is a straightforward conversion that requires nothing but a barrel change on a standard AR upper. This is a big reason why rounds like the 6.5 Grendel, 6.8 SPC, and many others failed to gain much traction in the AR market. The .300 BLK just made more sense and was a quick and inexpensive upgrade that didn’t require special parts.

State Your Case: 300 Blackout vs. 5.56mm NATO/.223 Remington

The other thing that accelerated the rise of the .300 Blackout was the availability of common bullets and loading components. The 2008-2016 suppressor boom saw the .300 BLK gain huge market share, and because guns, ammo, reloading components, and optics were readily available, it hit the sweet spot for many shooters. They could load their AR cartridges with the same bullets they used for their .30-06 or .308 if they wanted while using the same powder as their .357 Magnum.

The .300 BLK can be used with bullets as light as 78gr and has large as 240gr. It can be loaded supersonic at 2,800fps and subsonic as low as 800fps. It’s an extraordinarily versatile cartridge that performs well with virtually any barrel length from about 5” past 20”. These spectrums are a large part of why the .300 Blackout has taken the AR world by storm where others have failed.

The .223/5.56mm (we’re not going to go into detail on the minute differences here) is probably the single most common centerfire rifle round in America, and possibly the world at this point in time. The widespread, global acceptance of the 5.56mm cartridge means that there is a plethora of options available to shooters of any budget, from cheap M4 knockoffs to high-end precision rifles. Ammunition is made virtually everywhere and surplus loads are cheap and plentiful. High-end match ammo is all over the place as well as a variety of self-defense and hunting options.

The availability of .223/5.56mm weapons and ammunition make it a hard to ignore. A person today can arm themselves with a decent AR rifle, a good set of iron sights, a few mags, and 1,000 rounds of ammo for under $1,000. It might not be a pretty gun, but you can always change stocks or grips later.

Although the .223/5.56mm has some issues as far as terminal performance in combat situations, it has more to do with the bullets used than the gun. Typical, inexpensive FMJ ammo lacks in comparison to hollowpoints or soft points, which are only marginally more expensive, but will perform much better in a fight.

The bullets are fairly light, with most weighing between 55gr and 77gr, of course with some outliers on both ends of that, but they are generally effective inside 500-800 yards on man-sized targets. The issues with this round have led to some to try to design upgrades, such as the 6.5 Grendel and 6.8 SPC, but they all fell short in several categories when compared to the round they were trying to replace.

State Your Case: 300 Blackout vs. 5.56mm NATO/.223 Remington

A huge benefit to the .223/5.56mm is ammunition weight. The light, high-velocity bullets can be carried in great volume in cheap, reliable magazines. This is a major consideration over .300 BLK, which can get heavy. A PMAG loaded with 30 rounds of 5.56mm weighs about 18oz, where a 30 round mag of supersonic .300 BLK can weigh about 22oz, and easily up to 30oz with heavy supersonic loads. Considering supersonic alone, you can carry six magazines of 5.56mm for the same weight as five loaded with .300 BLK.

For hunting, both the .300 BLK and .223/5.56 are limited to about 100 yards on most deer-sized game using the proper bullets. Despite what you hear today from the 6.5mm crowd, small bullets are still small bullets and a 5.56mm isn’t really ethical past 100 yards on a deer, but is fine on smaller game at longer distances. The .300 BLK is a great short-range deer round, especially for younger shooters and in states that allow suppressors for hunting. A large number of great expanding bullets exist for the .300 and many reliably open up at subsonic speeds. The .300 BLK is a national favorite for hog hunting.

So now it’s time to declare a winner. If ammunition supply and cost was not an issue, I would probably prefer the .300 BLK. I believe that it is a better round for more people and has a huge range of acceptable projectiles and end uses. The recoil is the same, if not lower, than 5.56, which means it is negligible. Overall, I think that the .300 BLK is one of the best rounds available for the AR-15, but…

State Your Case: 300 Blackout vs. 5.56mm NATO/.223 Remington
.300 BLK Mid America Munitions Broadhead fully expanded compared to loaded M855 5.56mm cartridge.

I think that the winner of this debate has to be the 5.56mm. The factors of cost and availability are impossible to ignore, as are gear weight and effective range. While not as powerful at the muzzle as .300 BLK, the .223 shoots flatter at distance and allows more effective marksmanship training. I think that the mass public acceptance of .223/5.56mm guns and ammo mean that it, although it is wanting on a few angles, the one to have in the stable for a rainy day.

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  1. Probably the wrong forum for this question, but which rifle round (below 12.5mm) will drop an elephant at 600 yards?

      • Bulit a blackout with one of my ARs. Used it one hunting season. Ditched the idea. Subsonic was still loud even with a can, and ballistics of both sub and supersonic were painfully primitive. Plus where to zero?

        .223 does very well what .223 does. 300BLK does little well, and is worthless for everything else.

        Blackouts are ok for personal defense and range toys. But to crippled for serious work.

        • Those subsonics you were using with the can- were those factory loads? Cause I’ve found that factory subsonic loads are uncomfortably loud, even with a quality can. But with handloading, you can get your loads very quiet, accurate, and still cycling reliably.

        • The subs were SIG branded subsonic straight off the gun store shelf.

          On the supersonic side, my -06 is quieter with the same can. There is a four inch barrel length difference, but still, the BLK left me scratching my head thinking WTF?

        • Couldn’t disagree more. Not sure your complete setup but I have shot 300blk on 5.5 inch barrels to 20 inches and I don’t think your being honest. If you say the 300 sub is loud suppressed then the 223 must be the voice of god.

          The versatility alone of the 300blk make it a better round than the 223. Super/sub suppressed/unsuppressed short barrel/long barrel, varmit hunting/medium game hunting.

          But since the article cares more on what’s the cheapest and easiest to carry for females the 223 definitely gets the win!

        • Many .300blk/ 300 Whisper balistic “arcs”, very well documented in various bullet styles and weights. Trijicon builds(as do others) .300blk reticles.
          Zero supersonic(110-125gr.) Bullets and the subtent drops are pretty accurately displayed for both subsonic(left side) and supersonic(right side).

        • @ John

          Seriously weird re:your experience with subs and a can in 300BLK. My experience is anecdotal, but running junk 200gr S&B subs, 208A-Max, and 220gr Harvester (on a SiCo Omega and SiCo Chimera for reference), the loudest thing left if the action (and the sound of the round hitting the berm if I’m at a range).

          My slowest 308s are much, much louder running either can. Sorry, no ’06 to use for comparison.

          Not discounting your experience, it is just weird compared to my own, and others that I shoot with that have 300Sub builds and 30 cal cans.

    • Meh, ignore all the 6.5 Creedmoor Trolls. Traditionally elephant hunters used very powerful rifle rounds such as .404 Jeffery, .416 Rigby, .416 Rem., .458 Win. Mag. or .470 Nitro Express.

    • I believe a firearm in the Nitro Express category might work, the problem as always is ballistic performance past 300 meters. -sarc

    • The greatest elephant hunter on record Walter “Karamojo” Bell frequently dropped pachyderms with a 7mm Mauser!

  2. Which is better, a Hammer or a Socket Wrench?

    It’s basically what you’re asking here.

  3. State Your Case: 300 Blackout vs. 5.56mm NATO/.223 Remington

    Uh… no. They are both good – at different things. Their peak usefulness peaks in different areas.

  4. 300BLK solves the stopping power deficiency of 5.56 out to 200 yards. 6.8SPC is a better choice for longer ranges.

    300BLK offer full velocity in short barrels.

    All of my defense guns are short barreled, 300BLKs.

    • Elroy is correct. 300 BLK became a SAAMI cartridge to act as a replacement for the 9mm, not the 5.56. It was designed for suppressed PDW use specifically to replace the MP5-SD as used by SOCOM and such. I realize it’s *extremely* difficult for people not to compare it to the 5.56 and try to determine which is better, but it really should be compared to the 9mm.

      • The nice thing is it’s a 9mm that can reach out to 300 yards with 7.62×39 ballistics with just a mag change, and its performance out of 8-10 inch barrels vs short barreled .223/556

  5. One problem with considering .300BLK vs 5.56mmNATO in this format is that it skips over the issue that the choice OUGHT TO be an Either/Or decision — which negates or greatly lessens the major argument made for the .300BLK.

    Having ARs in both calibers (or one AR with uppers in both calibers) is simply a kaboom waiting to happen. You can be careful, you can implement color codes and all sorts of other “safety” measures, but sooner or later one of your .300BLK rounds WILL find its way into a 5.56mm chamber.

    • Tested it out of curiosity, looked like the bolt was about a third of an inch out of battery. Not sure if the hammer would be able to drop with enough authority to actually fire it, but it’ll drop enough to make a click, at least (did that part without a round chambered). Still seems like more of a “be very careful” than a “never have these under the same roof” concern, honestly.

    • I see where you’re coming from, but I’m gonna have to disagree. If you can’t be trusted with two separate calibers I probably don’t trust you with one. Also 5.56 in a 300 rifle will make a funny noise/flash and your round will tumble out the barrel at a slow rate of speed. With 300 in a 5.56 rifle I’m not sure that I’ve heard of a single incident of this actually going off, but if it did I would imagine you would get the typical squib boom where the magazine shoots out the bottom and your rifle may be screwed but you’re 99% of the time going to be okay. Caution is good, depriving yourself of having the best of both worlds because you don’t trust yourself is foolish. Learn to take care with what you’re doing and make up your own set of rules. I keep 300 and 5.56 in different ammo cans which are never opened at the same time, use different tinted lancer mags (so they’re color coded and the rounds are visible) and simply pay attention to what I’m doing.

      • It happened to me. Took my nephew out shooting. Gave him the .223, I had my .300 AAC. At some point he put a .300 in the mag. BOOM. Open chamber det. Pretty much destroyed the upper. Bullet made it about 10″ down the barrel. Broke the mag release. I color code my .300 stuff but learned never to bring them out at the same time. Trust me – a .300 WILL fire in the .223 chamber.

        • I imagine this is especially the case with subsonic 300BLK, the lower powder volume allows the bullet to be pressed back too far into the casing when loaded in a 5.56 chamberand now you have a nice little bomb. Load your own mags, and don’t bring both guns out at the same time.

        • DM, that or a 125gr. with a slender ogive could potentially squeeze in. Or if your bullet isn’t crimped in very well it could get shoved back.

        • ” At some point he put a .300 in the mag. BOOM. Open chamber det. Pretty much destroyed the upper. Bullet made it about 10″ down the barrel.”

          10 inches down the barrel?

          Can someone explain how a .30 cal bullet went 10 inches down a barrel bored to .223- 5.56 Nato?

        • Geoff, Fed Up. I’m shocked there aren’t at least a dozen more replies to your statements. The material just rights itself.

    • Lol ok Einstein, just because you’re too stupid to own both a 300bo and a 5.56 without exploding your rifle doesn’t mean the rest of us are.

    • I agree. A better comparison would be the 300 blk to 277 Wolverine. Both require only a barrel change. And both parent cartridge is the 5.56/.223. Stop beating the. 223 vs 300 blk dead horse.

  6. I own both. I have a dedicated 9inch bcm 300blk sbr loaded with 110gr vmax. This gives me a fast handy rifle with almost the power of 7.62X39. I use this for home defense specifically. Though it’s a very versatile setup and can be used for most tactical situations.

    My duty rifle is a 14.5in bcm enhanced lw barrel 5.56 with a permanent 1.5in battlecomp. Very light weight and stupid accurate from my experience.

    I’ll go to war with either one.

  7. 300Blk if you need CQB, 5.56 if you need a little more range out to 300M… beyond 300 meters… you should really be using a bigger cartridge, .300, .308, 30-30, 30-06, a flavor of 45 or even a 50BMG…
    7MM and 8MM are both good as well…

  8. Slightly off topic, but when it comes to handloading, CFE BLK powder actually does more for 7.62×39 than it does for .300BLK

    I’ll take 7.62×39 at 2,550+ fps (manufacturers max published load) with a 123gr bullet out of a 16 inch AR all day long.

    • 22winmag……I use the 7.62×39 also. Wish the bullet manufacturers would quit ignoring this caliber and start making some different weight bullets like they do for the 300.

    • I agree. I can’t personally vouch for the 7.62×39 loaded with CFE Black but when I looked at Hodgdon”s charts I went with Lil’ Gun for my 300 Blk Out because it had the advantage of more velocity with less powder.

    • No, but Springfield, S&W, and SIG, just to name a few, build Glocks in 9mm, the 6.5mm Creedmoor of the Pistol World.

  9. If we keep click on JW’s awful caliber articles, he’s just going to keep going. Do not feed into this dimentia.

  10. Just get an ak 10.5″ or 16″ , thats what we are trying to out due 7.62×39 is a deadly round just like the 5.45×39 and ammo is cheaper

  11. I’m with TOM C – I Only Have and Will Ever Have Another AR-15 Chambered in .223/5.56 (Currently have a Ruger AR-556MPR), as for a PDW I Have My Springfield Armory XD(M) 3.8″ 9mm Modified with a set of Talon Grips and a L.E.D. Flashlight/Laser Combo – It’s Extended Mags Hold 19rds, So If I Can’t Neutralize a Criminal With It I Guess I Deserve To Die/It’s My Time To Die…

  12. Geez Josh, maybe in your next article you can compare fishing boats vs. Mini vans? Because they both fit in a garage.

    The fact that they are designed for different purposes is irrelevant, right?

  13. Just got a 13.5in .300 BLK barrel for deer season, I have no plans to suppress it, nor do I think anyone should bother with using subsonics for hunting, they just don’t have the energy to take game cleanly. I don’t see it as a competitor to .223, it’s a competitor to 7.62×39 and at that, it excels. I use either 123gr or 150gr ballistic tips and for deer-size game inside 150yds they do just fine, for literally every other purpose, .223 is the clear choice for me.

  14. .223/5.56 sucks. But then again, so does .300 BLK.

    There’s one place where .300 BLK is far superior to .223/5.56 — in a short barrel rifle. .223 is basically a .22lr-sized bullet sped up to enormous speeds; if you cut the barrel length down to 7.5 or 9.5 inches or so, you cut the cartridge off at its knees (or its balls, more likely). You end up with something more like a .22 magnum. .223 needs a long barrel, bare minimum 16″, to develop the velocity it needs to fragment the bullet properly.

    Folks who want an SBR, run (do not walk) to the .300 BLK instead. It’s designed to be fully effective from a 9″ barrel. It overcomes the pathetic weakness of short-barrel .223.

    .300 BLK subsonic is a joke for a rifle round. If you want subsonic in an AR platform, ditch the pew-pew of the .300 BLK (which is barely better than .45 Auto from a Glock 30) and get a real subsonic round, a 500-grain or 600-grain .458 Socom.

    • Yep, all of this. 223/556 sucks but at least it’s semi-affordable and is an adequate varmint round. 300BO does not need to exist.

      Need a subsonic semi-auto? 45acp in a PCC will so just fine.

      Need supersonic 30 cal for hunting? 7.62×39 or 30-30.

      Bigger than 556 with better long range ballistics? 6.5 Grendel.

  15. While all of you argue about .223/5.66 vs .300BLK, I’m taking my 45lb long bow out with a couple of broadheads and catch me some deer during archery season while you bozos argue about which rifle round hits harder. Obviously, a broadhead on an arrow shot out of a bow has more power that any of your rifle rounds and with string silencers makes less noise than .223/5.56, .300BLK, .308, 30-06, etc. Otherwise, just use 50 BMG and solve all of these issues. Besides, who wants to hunt game from two states away. A dead deer is a dead deer; venison by any other name.

      • My 55lb compound bow is more powerful than my my 45lb long bow, but my point is that the 45lb is more than adequate to take a deer. The compound bow is too accurate with its sights and all (can’t wait to put an archery red dot on it) that is makes archery no fun. BTW, I saw a photo recently of someone who took an elephant with a bow.

  16. What bullet is that 300 BLK silver tip??? I want to reload it. I have a 14.5″ 300 BLK and a 14.5″ 556. A bit more muzzle blast from the 556. The 300 hits a kicks a bit harder. Both are fun.

  17. To me it is very simple, 5.56 is a general purpose carbine cartridge, 300 blackout is a great suppressed cartridge, other than that there are better cartridges out there for everything else. 300 ham’r Is a better supersonic cartridge for the AR and it will catch on. Try a 5.56 vs 300 ham’r State your case.

  18. 1. 223/556 great Varmint round only good for coyotes and smaller. You only base you choice on it being cheap to shoot?
    2. 300 BK More effective on larger game. The only people that don’t like it are hung up on the subsonic loads. With super sonic (220gr@1550 FPS +- 44 mag!) it is good.
    3. 6.5 Grendel, verry good but super thin bolts crack too easy.
    4. 6.8 SPC the perfect choice!!

  19. Depends on use.
    Silenced room clearing? Subsonic 300blk.
    Medium game hunting? Supersonic 300blk
    Small game hunting? .223/5.56

    Self-defense, End of the world rifle? 5.56 NATO.

    Generally speaking, standard NATO cartridges with widespread ammunition and magazine availability wins hands down every time. But in this case your firearm should be cahbered in 5.56, or .223 Wylde.

  20. Two separate animals for two separate purposes. It’s like hog hunting with dogs; hounds for tracking and bully breeds for catching.

    Simply keep your two different ammunition in two separate types of magazines. I use regular USGI mags for all 5.56/223 ammo and Lancer mags for 300BLK. In the dark, in a hurry or simply reminding other family/friends at the range with me that plastic means 300BLK.

    Author stated, “…it’s unfair to…say the .223 is bad by comparison because it’s louder.” Actually, we should ALL say so.
    ARs, especially when fired inside a building, may actually make you lose hearing from one shot even if you are wearing most hearing protection. Sorry Folks…Nature never cares.
    We should also say the same things about all firearms. One shot from almost any firearm can give you permanent hearing loss.
    Here’s the tricky part: The permanent damage occurs in stages. In the first stage, you may hear about the same after a few days (or not), but important parts of your ears just stopped regrowing correctly. With each passing year, that regrowth gets worse and worse until you spend all day like me: saying “What? I have a lot of hearing loss. Would you say that again?”
    And hearing protection often fails to cut it. And the biggest illusion is the idea that earplugs inside earmuffs will be twice as good. You’ll be VERY lucky to get 5dB more shielding that way.(3M has good info on its website on this.)
    I wrote more on TTAG in my article “Today’s Hearing Protection Doesn’t Work” , if you want it.
    I won’t be checking back in; that is all. Good luck when firing ARs…you’ re gonna need it.

    • What?? Can’t hear you, didn’t use an AR like you said, plus didn’t want to hit the neighbor’s dog, so I stuck with 12g. What’s that? Tuesday’s Sneering Projection a Dozen Snarks? Ever shoot any other calibers? I don’t find 5.56 louder that anything in rifle load I hear on the range except .22lr.

  22. I’ve stretched the 556 out to 200 on deer with little issue with quality bullets. I’m not going to run a can so I’m looking hard at the 300 Hammer specifically for hunting. The thing is that I’m not seeing a range gain so I’m still debating.

  23. if I had wanted an AK round in an AR15 platform I would have had one chambered in it. the 300 BS Hawk almost equals the 7.62×39 in performance, plus the 39 is tons cheaper to shoot and 39 is a good hunting round!

  24. Why cant it be both? In all your other “State Your Case” comparisons, you list two basically similar calibers that it wouldnt make sense to have both of, but 556 and 300BLK seem to be more complimentary to me. I cant see a reason to get rid of my 556 Carbine or my 300BLK SBR.

    If you are going to force me to choose though:

    If we are talking your first/only AR, get a 16″ 556 and be done. You’ll always be able to get ammo for it, its cheap to practice with, etc. I would never advise someone to get a non-standard caliber as their only gun.

    By the same token, I also don’t see a reason to own a 16″ (or greater) 300 Blackout. There isnt any significant advantage over a 556 in that length, and in a 16″ barrel you are going to have trouble keeping subs below the speed of sound, so it wont suppress as well. If you live in a state that wont allow hunting with a .224 caliber rifle, and you arent going short, then build a 6.8SPC or a 6.5Grendel. Both are a much better option for non-NFA supersonic only hunting calibers.

  25. “Although the .223/5.56mm has some issues as far as terminal performance in combat situations, it has more to do with the bullets used than the gun. Typical, inexpensive FMJ ammo lacks in comparison to hollowpoints or soft points, which are only marginally more expensive, but will perform much better in a fight”

    5.45 doesn’t have this issue in fmj form. MOAR air cavities get the job done and at the same price as FMJ 223/556.

    300 blk, meh ill keep my 7.62×39 ar (POF) that is the same size as a 223 ar, not 308 size, so throw that plus out the window for 300. Runs like a sewing machine with cpd/asc magazines so also throw that issue out the window. It also shoots rounds that cost 20 cents a pop compared to 50 cents with more ass on them. Until 300 blk ammo prices come down to what they’re actually worth (223 case necked to 30 cal bullet…both OLD and previously available) its not even worth looking at.

  26. “If ammunition supply and cost was not an issue, I would probably prefer the .300 BLK”

    Yeah, pretty much that.

    I like both, however, if cost was equal (in a blue pastel fairy land) and I could have 100/125 supers, and big fat subs, with excellent performance in short and long barrels, I’d take the 5.56s broad-shouldered (top-heavy?) cousin.

  27. The biggest advantage of the low power 5.56×45 is that ammo is available world wide and much is government issue surplus=cheap.
    For home or classroom defense the AR in 300 BLK is ideal, particularly with a suppressor.
    But the convenience of using the same parent case [ 5.56×45 or .221 Fireball] is what makes blowing up an AR almost a certainty for anyone who might have both kinds of ammo.
    I’d like to see a 10mm Auto case lengthened to 42 mm, with a rebated rim to 0.378 to fit a standard AR bolt. That case necked to fire a 7.62mm bullet could not be chambered in a 5.56×45 since the case body diameter is a mm too large.
    The extra powder capacity would make a 30/30 power level AR and still allow the subsonic quiet indoor/close range use of the 300 BLK.
    I think it would/could use a standard 5.56 magazine with a loss to 25 rounds

  28. Technically there is no case. If you have one cartridge, you automatically have the other. Just a simple upper swap. Seamlessly enjoy both! If you’re part of the NFA crowd though, you’ll be using 300 BLK way more often…. WAY more.

  29. A better question, much more “apples vs. apples” might be; What’s better and why, .223/5.56 vs. .222, price and availability be damned!

    .222 weighs less than .223/5.56, so l can carry more (where have we heard that before?) and it’s still a rocket-fast .22 bb-gun sized projectile, so how much better is the .223/5.56 since the tumbling on impact of the original 5,56 round went away when the original M16 rifling twist rate changed to more modern rates of twist?

    Armchair experts are strongly urged to pipe in. I’m a throw another log on the fire, put on my smoking jacket, and grab a snort of port. Fire away!

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