5.56 vs 300 BLK in a Short Barrel Rifle
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Ever since I first read one of Foghorn’s 300 BLK fanboy articles back in early 2012, I’ve been hooked on the caliber.  300 BLK gives you essentially the same ballistics as 7.62 x 39 out of the ubiquitous AR-15 platform with only a barrel change. Everything else in your stock 5.56 AR can stay the same and you get to use the full 30-round capacity of your 5.56 magazines (offer void in CA, MA, NY, NJ, etc., etc.). The caliber is designed to be shot both supersonic and subsonic and unlike many other gas piston guns, you don’t need to fiddle with the gas settings when you screw on a suppressor. Really, what’s not to like?  Well, pricing and availability are less than stellar, but 300 BLK is a cinch to reload and if you purchase clean and pre-sized brass from Carolina Brass, you can be cranking out your own rounds by the dozen in minutes with a very rudimentary reloading rig . . .

A while back, Foghorn told us about his latest project, a 300 BLK Short Barrel Rifle that had just recently cleared paperwork. That post prompted a lively exchange on a number of topics, one of which was the performance of 5.56 versus 300 BLK in SBRs. So I fired off an email to Foghorn and suggested that he do a comparison shoot off between 5.56 and 300 BLK in both full length and SBR length barrels and compare the results. Nick thought this was a peachy idea and in the meantime he sent me a link to a comparison someone else had done with 55 grain 5.56 and 110 grain 300 BLK in different barrel lengths from 4 inches up to 24 inches. For the curious, that chart can be found here.

But Nick’s a pretty busy guy and with my recent purchase of an AAC 9” 300 BLK upper, I had all of the tools I needed to do the comparison myself. With that in mind, I set up the following test:

For the .223/5.56 mm sequence, I decided to try both 55 grain and 62 grain M855 ammo.  I wanted to use M193, but didn’t have any kicking around, so instead, I used some Fiocchi 55 grain .223.


Test weapons were my 16” SIG Sauer 516 Patrol Rifle and my SIG Sauer 10” P556 pistol.


For the .300 BLK testing, I opted for Remington UMC 115 Grain 300 BLK ammo


and used both my 9-inch and 16-inch AAC 300 BLK uppers. For the curious ATF agents out there, you can relax. The 9-inch upper was mounted on a legitimate pistol lower receiver. Unfortunately, this isn’t exactly and apples-to-apples test. Ideally, the shorter barrel lengths for the two calibers should have both been either 9 inches or 10 inches, but one must work with what one has.


The test was conducted on the same day to minimize the impact of temperature and humidity differences. For each string, 20 shots were fired through my chronograph and the average velocities taken. Finally, the velocity of each load in each barrel was compared and the percent reduction calculated.

Average Velocity in Feet per Second

16 inch

10/9 inch

% Reduction

55 Grain Fiocchi .223




62 Grain M855




115 Grain 300 BLK




There are a couple of things to note here. First of all, remember that while the 5.56 round had to contend with a 6-inch reduction in barrel length (16 to 10 inches), the 300 BLK had an even larger reduction – 7 inches (from 16 down to 9 inches). Even with this handicap, the velocity reduction of the 300 BLK versus the 5.56 was very close on the 55 grain bullet and 6% less than with the 62 grain projectile.

In an effort to adjust for the one inch difference in barrel length between the two calibers, consider that the chart Foghorn sent me predicted a 9.35% reduction in velocity of a 110 grain 300 BLK round. This would put it relatively close to the measured 55 grain .223 reduction and much better than the 62 grain velocity reduction. Further consider that the same chart predicts an 11.7% reduction in velocity for the 110 grain test round when moving from 16 inches to 9 inches. My testing showed the reduction was actually even less – 10.11% so its fair to suggest that had I fired this round from a true 10 inch barrel, the velocity reduction percentage might very well have been even less than the 55 grain .223 reduction.

The second thing to keep in mind is that velocity tells only half of the story. To determine a round’s effectiveness, you also have to consider bullet weight. While it’s true that the 115 grain 300 BLK round that was tested had a lower velocity across the board than the two .223/5.56 rounds that were tested, the 300 BLK was also about twice as heavy.  In order to compare the three rounds another metric must be used to normalize the results – Muzzle Energy.

Muzzle Energy is a measurement of the kinetic energy of a round as it leaves the barrel.  Both bullet weight and bullet velocity contribute to total kinetic energy.  Because muzzle energy takes both weight and velocity into account, it allows us to calculate a single value for a particular load and enables comparisons between loads of different weights and velocities.  That said, muzzle energy is not the one metric to rule them all because as soon as a bullet leaves the muzzle, other factors such as gravity and aerodynamic drag start to impact the bullet’s flight.  Since the goal here is to draw a comparison and because I’m really bad at advanced mathematics, I’m not going to try and create a high level model that takes multiple factors into account.  Instead, I’m going to calculate muzzle energy, compare the three rounds, and then go get a beer.

Since I’m lazy, I used Verne Trester’s muzzle energy calculator to figure out the energy of each of the tested rounds.   Here are the results:

Muzzle Energy in ft-lbs.

16 inch 10/9 inch % Reduction
55 Grain Fiocchi .223 873.29 813.42 6.86%
62 Grain M855 1227.22 857.5 30.13%
115 Grain 300 BLK 1391.95 1124.80 19.19%

So, what were my conclusions?  Well, first of all, a 115 grain 300 BLK round has more muzzle energy inch for inch than anything in the 5.56 or .223 range.  No real surprise there.    What’s more interesting is what happens when you cut the barrel down.  The 300 BLK’s muzzle energy out of a nine inch barrel  was within 100 fps of the 62 grain 5.56 coming out of a 16 inch barrel and when compared to the 62 grain 5.56 out of the 10 inch barrel, it was no contest.   The 55 grain .223 bullet isn’t even in the game when compared to the performance of the 300 BLK.

In an AR-15 platform, there really is nothing that the 5.56 round can do that the 300 BLK can’t do better.  Sure, for very long distances, the 5.56 might have a slight advantage, but with his 9 inch barrel, Foghorn was able to ring the 500 yard gong with supersonic ammo and could consistently hit the 250 yard gong shooting the slower subsonic ammo.  We already know from the calculations above that once you cut the barrel down on a 5.56 round, you really impact its performance, so to keep up with the 9 inch 300 BLK SBR, you would need to retain your 16 inch barrel for 5.56.  Now, for real distance work there are still better AR-15 calibers – 6.8 SPC for one.  But then again, I have my .308 LWRC REPR, my 300 Win Mag Bolt Rifle, and my .338 Lapua for distance shooting, all of which will be superior to just about anything in the AR-15 platform.

A SBR is not likely to be something that I use for real distance work – it is a close-in gun.  Based upon the results of my testing, assuming that you can overcome the cost and lack of availability problem of 300 BLK (and you either own or plan to get a suppressor), the 300 BLK is my choice for SBR caliber.

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    • I’m glad I’m not the only one who noticed that. I don’t want to say “can’t be right”, but there is NOT a 50% diff between M193 and M855 like that. Something must have gone wrong in the calculator inputs.

      • Well, for one thing, M193 wasn’t used. Fiocchi .223.

        Still, I’m a bit surprised at the difference, too.

        • I’m on the road at the moment, but anyone who wants to verify my numbers can plug them into the online calculator referenced above. Bear in mind, this is a muzzle energy calculation, not a muzzle energy one. Bullet weight plays a role too. The 55 grain round is about 11% lighter than the 62 grain one. That, plus the lower muzzle velocity explains the muzzle energy difference.

        • Jim, I’m not arguing with you, but MW’s question was originally “Why is the fiocchi .223 velocity so low out of a 16″ barrel?” (emphasis mine) Of course the muzzle energy calculation is going to be lower if the original velocity is.

          (Also, you said in the comment above “Bear in mind, this is a muzzle energy calculation, not a muzzle energy one.” I’m not sure what that should have said.)

          But back to the original question. The question is, why is the velocity so low? You came up with a muzzle velocity of 2673, and a calculated muzzle energy of 873.29.

          Fiocchi’s numbers (from their catalog, here for that exact load are:

          Velocity: 3240 (muzzle), 2877 (100 yards)
          Energy: 1281 (muzzle), 1017 (100 yards)

          Unfortunately, their catalog doesn’t give a barrel length used in rifle round testing, but 16″ seems a reasonable assumption, as that’s most common. (EDIT: I didn’t see L1A1Rocker’s comment below about many manufacturers using a 24 inch barrel. If that’s true, how much would that increase the velocity over a 16″ barrel?) So why is the velocity value you got (average of 20 shots, according to you) a full 17.5% lower than Fiocchi’s stated test value? That velocity difference leads to a whopping 32.5% difference from Fiocchi’s stated energy value.

          Why do you think your velocities were so much lower than Fiocchi’s stated values?

        • “Bear in mind, this is a muzzle energy calculation, not a muzzle energy one.”

          Uh, could you elaborate on that a bit?

      • .223 is a low(er) pressure civilian cartridge, versus the military 5.56×45. You’ve heard that there is a difference between the two — here it is.

        • The pressure difference is not _50%_. In fact, the main difference is not pressure, it’s the chamber measurements.

          Again, that number almost certainly is wrong, and I’d like to see the author confirm it for us.

    • This has come up A LOT with the 300BLK comparisons. The biggest problem is that most all (even the 223 and 556) ammo manufactures’ list their velocity using a 24 inch test barrel. The 300BLK is the only cartridge I know of that has SAAMI specify a 16 inch barrel.

      • You might want to double check the SAAMI database. All rounds are listed with a velocity as measured from a 16in barrel. All rounds, even pistol.

    • Well 223 is factory round it not going be as hot m855 it is a armor round.so the velocity not going be as strong just a couple grains of powder Rise the vevelocity and the type of powder i hope that helps

  1. The issue with 300 AAC is that it is inherently designed to be a short range round. (<300 meters) While, just like the 7.62×39, that is an admirable goal, it leaves it lacking on an open battlefield where full length 5.56×45 rifles and battle rifles (.308) are king. In my opinion, 300 AAC SBRs are the ultimate replacement for submachine guns. That's what they ultimately need to be compared against. Sadly, the .300 AAC round simply does not have (due to ballistics) the ability to meet as diverse a group of battlefield needs as the 5.56×45 round.

    Can’t fault your science approach. (I would have added bench group tests at 50, 100, and 300 yards.) But otherwise excellent. In the future a statistical analysis of the muzzle velocity of the different rounds tested would also helped. (Mean, median, Standard Deviation, etc)

    • The average infantry engagement range is well under 300m. The whole reason for 300 BLK development in the first place was for more effective and efficient firepower on the battlefield over the 556… plus other perks.

      • Don’t forget Mike, that the 300 meter number was developed based on an urban European battlefield. Some place like Afghanistan with multi-killometer unrestricted sight lines is a bit more problematic. I don’t disagree that the .300 AAC is a great round. There are plenty of things it does better than the 5.56×45, but it is not the jack of all trades that the 5.56 is. I can hit man sized targets with a 5.56×45 rifle and iron sights at 500 meters. It is much more difficult to do so with the AAC because the round has lost stability long before then.

        • “the round has lost stability long before then”.
          Huh? Do you have a source for that? I’ve never had an issue hitting at 600y with mine. Other people with access to longer ranges have hit at 800y with it.

        • @Jason
          Unfortunate side effect of going from super sonic to sub sonic flight. When the bow shock collapses it causes the round to start tumbling in an unpredictable fashion. The problem with the 300AAC is that since it has much more drag and a lower initial velocity than a comparable 5.56×45 round it goes sub sonic sooner and starts tumbling. Most 300AAC ammo out of an intermediate barrel makes that transition at between the 350 and 450 meter mark. At 500 meters the round is tumbling and precision shooting is as much a matter of luck as skill.

        • “because the round has lost stability long before then.”
          That is total 100% complete BUNK!

      • Mike,

        Engagement distance is a very temporary concept. Across a battlefield with iron sights, in WWI the US forces impressed the Europeans with accurate volley fire at 600 yards. One war later, urban and hedgerow battles were the game and still using iron sights, the engagement distance was significantly reduced. Next war, snipers were more effectively employed and target detection was available at longer ranges. Yet, many soldiers held fire until closer distances because of mass attacks being fended off with crew served weapons. Next war, the US was fighting in a jungle and camouflage was key.

        I participated in the Invasion of Panama carrying an M16A2 with an M203. Very few shots fired, no war stories of note, but I was never called upon to make only short shots. Even in a modern cities the distances can be stretched. A man wearing a camouflage uniform stands out against concrete walls. During Desert Storm, everyone could have used optics but they were not readily available. I bought a mount for the M16A2 and a simple scope at Walmart before reporting. Next mission, thankfully I switched to the MPs and only carried an M9. Never asked how far the troops were engaging in Bosnia but I have walked Sarajevo and the range some shots could be made is LONG. Back in Iraq in 2009, we were in Mosul. Engagements ranged from 3ft to the other bank of the Tigris. Soldiers were quickly trained on the updated M14 and even soldiers with ACOQ equipped M4s could fend off “snipers”.

        Point being, too much of the notion of engagement distance is temporary. Were soldiers using iron sights or optics, flat or hilly terrain, villages or modern cities? All of that matters.

        I don’t use .300BLK for the same reason I don’t own a .40. I already own a 5.56 and a 9mm. Any error that lead to cross feeding ammunition would be tragic. But I don’t see any real advantage in .300BLK that tips it in the direction of adoption for a US service rifle. 5.56 already wins on supply economy. 5.56 has more range. With optics, it pushes back the range of engagement.

    • At 600y, my 300BLK out of a 16″ barrel is still over 1400fps* with a 147gr bullet. And I’m able to score hit after hit on an 10″ paper plate from a supported standing position. I’d say that’s pretty good intermediate distance performance.

      If I want to shoot past that, I’ll pull out the 308 bolt action and the tripod.

      *Based on the Shooter iPhone app calculations, which are probably spot on, because the elevation adjustments for the scope are.

      • I’m not sure how you managed to get a 30 caliber projectile to stay supersonic at 600 yards with the powder in a 300AAC case. What’s your muzzle velocity on that load?

        • Works pretty good for Travis Haley too. Perhaps the question is why you are having such a problem. Or are you just posting your musings and not real experience with the cartridge?

        • @L1A1
          I’m actually curious. Every load I have tried calculates to go sub sonic ~450-500 meters (Max, typically it’s much less than that for heavier loads). I don’t shoot long range with 300AAC. (Don’t have the right rifle for it.)

  2. Since the marketing of said 300BLK has reached the 45 v 9mm wars level, I ‘ll put my two centavos in. To the millions of AR owners the suppressor option is purely academic. Much like the fantasy supermodel date. So that is off the table in my argument. SBR same. As for improving the AR platform cartridge the 6.5 Grendel does it for me. Check out the long range numbers on vel and energy. Low recoil, heavier bullet, better trajectory with unbelivable BC and the argument is over. Other than the Grendel, if Hammer of Thor is required, the 458 Socom fits the bill.

    • One thing to remember is that the round was designed with a specific goal in mind. (7.62×39 ballistics and superior suppressor performance.) It was not designed as a complete replacement of the 5.56×45 round, and is not such because it can’t fit all the same battlefield roles. (Very poor comparative performance in the 300-550 meter range band.) However, it is an amazing replacement for 9mm and 45 ACP submachine guns.

    • Just ignore the silencer/SBR angle?? No freakin way. Would I wait almost a year to date supermodels?….hell yea lol.

    • This guy has it straight.

      Why bother with the 6.8 SPC when you can get something that has way way less of the downside? Why use 300blk when you can slap in what amounts to throwing a roll of quarters at someone in hallway distances. 6.5 for all around performance any day. .458 for those moments you want to put down Bigfoot with a grazing shot.

      • So use 2 niche calibers and 2 rifles instead? No thanks. I’d rather just swap magazines on 1 rifle. Is there a performance compromise compared to the 2 separate calibers? Sure. But it’s probably worth it in most scenarios.

        • +1
          Logistics make or break this argument. The .300 AAC round is a great compromise cartridge if you don’t need to engage targets beyond 300 yards. The reality is that in any situation other than a bench shooting contest, the simplicity of using a single caliber gives you a rather large logistics advantage.

  3. Luckily, the AR serial number is on the lower, so you can have any number of SBR uppers with one tax stamp…

    As I understand it, the 300BLK burns all of its powder in the first 10.5″ of barrel. With a 9″ barrel, you might be shorting yourself that last little bit (as you noted).

      • Me, too. I suppose that does not mean that pressure is ambient at 9″, tho, the projectile no doubt continues to accelerate for some distance after all powder has burned. Wish I had already figured that out when I chose 9″ instead of 11.5″. Of course, I suppose I could buy a barrel …

  4. The most important pro 5.56 ammo has is that it is easier to obtain and cheaper to train with. If I had a toy SBR I might go with a BLK build but my “serious” guns all shoot 55 grain stuff.

    I can’t stress how important using 55grain stuff has been for my shooting. I have witnessed my skills increase from simply shooting more often and critiquing my performance with each range trip. I wouldn’t be able to shoot as often if costs went up from where they are now.

    I can’t imagine a scenario where 300blk will ever be cheaper than 5.56.

    • I’m with you on that. Better an affordable bucketful to train with and $$ left over for bespoke ammo than chase after limited supplies of 300 BLK.

      Off to the range today, in fact, to zero out a coupla scopes.

  5. This is old news from 2 years ago already. But at least now the numbers can be proven by consumers themselves now that 300 BLK hardware is finally available in reasonable quantity. Wish ammo was the same.

  6. Your missing the point: This is the second “Article” in a week where Carolina Brass is mentioned

  7. With all due respect, this test seems flawed to me. You tested .300BLK that’s going for a buck a round. What about using similarly priced 5.56×45, preferably with a very heavy bullet (75-77gr)?

  8. The problem with all of these 5.56 improvements – 6.5, 6.8, now .300 – is that they break up an already small niche into even smaller pieces so no one of them will ever get the market mass to move out of the $1.00 a shot boutique range. Which is exactly why they’re stuck in such a small niche to begin with.

    This being the case, since you’ve already thrown away any notion of economy or retail availability, why stick with the limitations of the .223 case at all?

    • 300 BLK isn’t niche whatsoever. At least not supposed to be. It’s just an AR-15 with a barrel change and a shortened brass case. Unfortunately it’s a new caliber that coincided with the worst political/social anti-gun environment ever. Sucks for us that’s for sure.

      • Respectfully, that “barrel change” is a pitch to an armorer or procurement guy. These are all dedicated uppers for individuals. So its really just a fins on Cadillacs argument. If you like it, have the money, can afford to shoot it, then blessings be upon you. If you don’t like it well, there are other supermodels at the dance…LOL

        • Ok fine, realistically it’s an “upper change.” Actually that’s even better and faster than changing just the barrel lol.

        • Seems to be it is easier and better to buy an entire new or use AR-15 rifle in 300 aac instead of buying and changing the barrel of my 223/556 AR-15. If I wanted to go with 300 aac. The uppers I have looked at online are almost as much as a good deal on a complete rifle.

    • If we want cheap 300 ammo the US must re-open imports from countries now shut down.
      If the developers of the 300 had cost effectiveness in mind the bullet dia. would match that of the 762X39

      • You can use the .311 bullets just fine. No they won’t blow up your gun. But what they don’t do is have the right profile to reduce drag and fit better in the magazine.

    • I wouldn’t coin it “improvement” but more an alternative option to 5.56/223. Basically like a SUV vs Truck use. You don’t use a SUV when you need that bed to haul larger things, but then again you don’t haul large items on a daily basis (or do you?).

      IMHO the limited range of the 300blk is its only downside (If ammo becomes more available or you reload). I like both rounds but surely the 300blk shines in SBR and suppressed form.

      • I would think the 300 blk is more a svu/truck crossover like the Avalanche. Where as 5.56 and 458 SOCOM would be suv’s and trucks.
        On another note If you compare the 77gr “5.56 NATO” to a 125gr SMK 300blk they have very good ballistics out to 300 yards. There should be an article on them!

  9. I think .300 BLK is an excellent round…if you have an SBR and a suppressor. In my opinion, the .300 BLK is really only a viable option for those that reload, so that you actually have the ability to put a good number of rounds downrange without breaking the bank. As someone else stated above, it makes a nifty replacement to submachine guns in an SBR, but I cannot really see any other real world applications for this niche round that another round doesnt already do better.

  10. Having shot Nick’s 300blk rifle with an sdn-6 on it, I’m……still not sold. If you do hunting its great. At “texas deer-hunting” distances 300blk suppressed is hard to beat with a 9″ barrel.

    I’m still just not ready to pay $1/rd or even $.50/rd for ammo. I’m not going to put just one round in a guy if he is in my hallway, I’m going to put multiple.

    Even nick can tell you I was a bit…on the fence still even after shooting it.

    • How about being able to shoot without ears on all the time? I think that’s a nice little perk…granted you already paid your dues to Uncle Sam.

  11. If we want seriously cheap ammo, we’re going to have to start leaning on the chinese and russian militaries not ours to adopt these niche rounds. You see the deal with 7.62×39.

  12. I like the idea of .300 BLK but there are more cost-effective ways of getting 7.62×39 ballistics. Buy an SKS or AK47.

    • You will find that many people also have those guns already, myself included. That’s beside the point.

      What were after is a round that is easily adapted to the AR platform and also reliable. Lower price is a plus, but most new calibers are not cheap in the beginning.

  13. Having just purchased a AAC 16 inch upper yesterday, the article makes me feel better about the purchase and comments have given me pause.

    I do think, if we get down to brass tacks, that I will be going with a 5.56 rifle. I have several, so 300 BLK will be a nice diversion.

    • Go shoot it and have fun. If you reload it’s actually pretty cheap. I suspect that the posts you’re reading are from the 6.8 fanboys that HATE anything 300BLK and will do anything to try and rundown the cartridge. LOL, for a lark and a bit of fun, run over to the 6.8 forum and search 300BLK, and 300WTF (yest they are that infantile). Talk about some real HATE going on there. WOW!

      • Yes the 6.8 crowd shows up most anyplace on the internet that discusses the 300BLK just to try and run down the cartridge. For some fun go over to the 6.8 forum and search 300BLK and 300WTF (yes, they really are that infantile) and laugh at all the illogical hate they have for the 300BLK.

        • Illogical hate? No, disdain. You talk about this round like it’s something new and amazing, but the .300 Blk doesn’t do anything the 7.62*39 can’t.

        • Except run in an AR platform with nothing but a barrel change, and run (as designed) subsonic and/or suppressed.

        • Who swaps barrels? Seriously? You can get an upper for 7.62*39 and nothing prevents you from using it in a suppressed sbr. So again, the .300 blk can’t do anything the 7.62*39 can’t.

      • 6.8 beats it on velocity, BC, SD, penetration, and trajectory. 300WTF is actually a rip off of JD Jones’s cartridge so a company could find a niche to exploit the industry even further and hype something that is an inferior design for supersonic rounds. The only, and I say only thing it has going for it is it’s 220gr suppressed options in keeping it under 1180fps. The 30 AR tried to do the same thing but didn’t have the backing or subsonic- suppressed factor. So basically, they jumped off the shoulders of J.D. Jone’s work and tried to claim a big part of the market for something they didn’t invent and the Russian 7.62×39 already did but was in .310 to .312 caliber and not USA enough! They took a lot of pictures of 300WTF dressed with suppressors to hype it as sexy.

        It isn’t a good cartridge and I have shot and owned both it to say this. It is a niche cartridge that is inferior to others that have superior ballistics and terminal performance.

      • You’re right, but as long as owning a supressor means giving the ATF permission to enter my house any time they demand it I won’t be buying a supressor. The supressed characteristics of the 300 Blk are therefor of no bearing to me.

        • How does that permission apply when the silencer or SBR is owned by a trust, and you’re just the trustee? Is it that you have to “give access?” Because I’ll be happy to let them inspect my tax forms and serial numbers in the driveway, or at a neutral location.

        • Owning a suppressor does not mean giving the ATF permission to enter your house any time they demand it.

          This site is called “The Truth about Guns” (emphasis on Truth), so let’s keep it that way please.

        • Same holds true for the SBR, or both together. *NOWHERE* have I agreed for any LE to enter my home without a warrant to “inspect” doodleyshit. They do, of course, know my address, can send me a letter to request access, I really do not believe that will ever happen, but my suppressed 9″ 300 BLK will never be my only gun so who cares?

        • I *think* (somebody here knows the truth) that owning a legal machine gun (or perhaps being a dealer) includes the unannounced inspections without a warrant, but suppressors and SBRs do not.

    • So where’s the love for 6×45 (6mm-223) or 6×6.8? There are a slew of boutique AR chamberings and they all have something good to offer the field. If they didn’t they wouldn’t be around…

  14. Jim,

    I was the one that suggested the .300 BLK or 7.62x39mm as better for SBR on your prior article — thanks for the followup! I thought it would work out that way.

    The el-cheapo way to get there is with a SBR’d AK-47 pistol. Cheap ammo, similar weight and velocity to .300 BLK and expected decent SBR performance. Going the 5.45x39mm route gets you cheap mil-surp ammo but 5.45 and 5.56mm depend greatly on velocity for terminal ballistic performance, while 7.62×39 and .300 BLK get there with larger projectiles, both in diameter and weight. The 5.45x39mm would not be expected to differ significantly from the 5.56x45mm numbers.

    • “…customized..” That says it all right there. Although i’m pretty confident a totally stock 300 BLK SBR will outperform it.

  15. I will abstain from this modernization of a 45acp vs. 9mm style argument/discussion… just as long as a 300blk rifle/carbine/pistol is NEVER called a “battle rifle”. “Ain’t nobody got time for that.”

    • WHAT?

      so you’re saing the M4 is not a battle rifle?

      we’re talking about the same exact weapon system (which is the “battle rifle” part) with a BETTER, far more versatile cartridge.

      which section of that knocks it out of battle rifle status?

      • jmkcolorado, a weapon platform does not itself make a “battle rifle”, if it did then a .22lr AR platform would be a battle rifle too.

        Don’t get your panties in a bunch just because you want do defend 300 blk from all attackers, this round has serious distance problems, especially if it doesn’t go as far as 5.56. What makes the M4/M16 a pseudo battle rifle is its versatility, portability, ammunition availability, and the ability to perform in open combat at longer ranges with decent takedown power.

        If you would please take a breath and clear your eyes you would see that I did not claim that it was not a proper PDW round, but rather that it does not fit the role of a battle rifle. Extended ranges are elusive to pistol cartridges, and the 300 has the downfall of being underpowered for its size. You can’t always have your cake and eat it too, 7.62×51 is perfect for the battle rifle role and a suddenly popular “wildcat” pistol round is not going to overcome the longer distances. 5.56/.223 is a compromise round, and takes some of the shortcomings of limited distance with it, but overall it fits the needs of the Soldier.

        SBR, close quarters combat, PDW, suppressed, range toy, 2nd upper… all descriptive terms for 300 blk. Don’t attempt to attribute “battle rifle” to it too. Just saying. In the words of Monty Python, “Now go away or I shall taunt you a second time.” http://youtu.be/9V7zbWNznbs

        • Daniel, what you say makes perfect sense, even the “pistol round” crap, if you think 220g subs are the only ammo available for .300. But it makes no sense at all when you consider loads all the way down to 110g. I bought mine for the 220g subs, but have plenty other weights, which are far more powerful, while louder. Versatility! You have cleared the area within 100 yards, but have threats at 500? Oh, darn, I need to swap mags.

          BTW, from behind the trigger, the suppressor works fine with supers, as well. Sonic boom moves forward, no problem.

    • Whoa there, let’s not get carried away here. I am amazed by this feat, but it is just that… a feat.

      Here’s one of the summarizing quotes from this article. “That being said, the 300 Blackout is really not designed as a long range round, both the Blackhills Mk 262 77 gr 5.56mm and the WOLF Performance Ammunition Gold 120 gr MPT 6.5 Grendel out perform it with ease.”

      Props to the author for his efforts and skill, as well as Noveske and PNW Arms (hat tip Nosler bullet) for their quality hardware.

  16. I don’t care about you having am SBR upper. What I want to know is where did you find the 115gr., Remington 300 BLK ammo ? ?

  17. Im tired of people bashing the 300blk because it is not super accurate at 500 yards. Ive served in Afganistan in those open engagment areas where the ball it stop flying before it hits a backstop. There are a very small amount of people who can accurately engage targets beyond 300 yards. Truthfully with the standard army red dot that we use (aimpoint) most people are more suppressing targets at 300 yards then they are trying to pip the ace. At that distance a hit is as much luck in a combat scenario as a well aimed shot so if the 300 blk has more ‘knockdown’ at that distance thats what really matters. Im not sold on the 300 blk yet it shows more effectiveness in the hands of an average soldier then the 223.

  18. It continues to amaze me how some people miss the purpose of 300BLK. Its not an all-purpose round, nor was it meant to surpass/replace 5.56 or 6.8 or 7.62 etc.

    It was designed as a .30 caliber cartridge that works well in an AR/M4 platform for short to medium ranges while using all the readily available parts except the barrel. Anyone putting it down due to range limitations is on a tangent. You don’t drive your truck long distances to get good gas mileage, do you? Would you also use your 7.62×39 to shoot past 600yards?

    The adaptability between short-barrel and suppressed use is a Major advantage. Reloading your used 223 brass is also great, along with having a myriad of bullets to choose from.

    • But, the 6.8 spc and 6.5 Grendel do this super sonic thing a lot better in BC, Trajectory, SD, etc.

      The only category it is good in is … subsonic work. Supersonic ? Really? 2100fps with a 125gr bullet?
      1900fps with a 150gr bullet?

      A 30-30 carbine does this a lot faster at 2500fps for a 130gr and better for $350 complete- 200yd advantage. The 6.8 drives 120gr SST’s 2500fps at least and if you reload, 2600fps. What that means to people in the know of ballistics is the muzzle of a 300WTF is equal to a bullet from a 6.8 SPC at 200 to 300yds. I would rather take the faster bullet with better SD factor and BC than a hyped photo shoot queen in the gun rags. Even the 30-30 is better and how old is that cartridge compared to the 300WTF? Ha- so much for engineering feats of the 21st century and after J.D. Jones did 99.9% of the lifting! So tell us all again… What was it created for? NIche market to charge people $1000+ uppers and claim it is the cat’s azz- MARKETING STRATEGY!!!!

      It has one category- subsonic work where it is good. The other category, the 7.62×39 and 30-30 out perform it and are 1/3 it’s cost for a complete weapon system for the money. For an AR platform, the 6.5 and 6.8 blow it out of the water.

      Those are FACTS!

      • Here’s a fact for you; not everybody gives a rat’s ass about the absolute cheapest way to solve a single problem. My 300 BLK fills a bunch of possible uses, plus the suppressor works real nice on 2 different 5.56 uppers and a .308 AR. I wouldn’t try using your 6.8 suppressor with a .308. And, I just may have to get a 6.8 SBR upper at some point (since I already have the SBR lower), and the suppressor will work fine on that, too. Fanaticism has no place in the truth about guns, except (of course!) in the PISTOL caliber wars.

  19. My primary – actually, almost *exclusive* – use of an AR is for the hoardes of wild boar in the eastern Carolinas. Never even thought of engaging one out 200m or so … because you don’t have to. You can get some excellent opportunities in the 80-125m range all day. Even that close, the 5.56 / .223 is marginally effective for a one-shot drop. But the .300 BLK? No contest. One shot and fire up the smoker … WE’RE MAKIN’ BACON!!!!

  20. This article misses one very important fact. With very few exceptions most modern rifle bullets suitable for hunting or defense offer no consistent fragmentation or expansion below 1900-2000 FPS. Optimal expansion generally requires 2200+ FPS. The exceptions to this are the .308 110 grain Barnes Blacktip which offers limited expansion to 1375 FPS and the .224 Nosler BSB which reportedly will expand to 1600 FPS.

    Respected experts in the terminal ballistics field such as Dr. Gary Roberts tell us that muzzle energy is not a reliable indicator of a bullet’s ability to cause incapacitation. Rather the permanent wound channel created by the bullet is the number one factor in determining effectiveness. Working with those facts the 300 Blackout SBR at the muzzle is right on the threshold of no expansion or fragmentation with nearly every .308 bullet currently available (The exceptions are 3 limited production Barnes bullets). The higher muzzle velocity of the 5.56 SBR gives it a much more practical buffer against the point at which rifle bullets no longer expand and act as an FMJ. This further negates the effectiveness of the 300 Blackout since the non expanding round would pass through the body without imparting all of it’s kinetic energy into the target.

    • You said that muzzle energy isn’t a reliable test for effectiveness and go on to describe how current 30 cal rifle projectiles (with few exceptions) won’t expand at the velocities that the 300blk produces. I’m curious what the average expansion (and cavity) would look like on a .22 caliber bullet? potentially nit much greater than .30.

      It any case, the take away here is that this caliber is quite impressive if you have the ability to reload. You can push 110r projectiles in upwards of 2800fps, and 240r pills just below supersonic speeds.

      My concern with 5.56 is, it’s effectiveness is reliant on hydrostatic shock. Without it, you are just punching .22 caliber holes. even if it does shoot flatter than a 300blk, how effective is a 800 yard shot with a .22 cal bullet moving at 1500fps?

  21. This is no replacement for the 5.56 NATO lol!!!!
    Vel at muzzle 16″ KE Sec. Den Ballistic Coeff Eff. Range
    Hornady 75 gr BTHP 2750 fps 1260 .214 .395 500 yards
    Hornady 110 gr VMX 2375 fps 1377 .166 ,290 300-350 yds

    The 300 AAC drops too much after 300 yards so it is a shorter range cartridge. the 75 and 77 grain loads are pretty much commonplace now in 5.56. Unless you are hog hunting once in a while, or need a load for an SBR for specific applications, this is nothing more than an attempt to replicate 7.62×39’s mediocre ballistics in an AR-15. You are replacing an intermediate cartridge (5.56) with another “shorter-range” intermediate cartridge (300 AAC black out). This is illogical The 5.56 is a good all-around cartridge (like a rating of B-) but if you want to improve, the .308 NATO is the next logical step not muddling around with underpowered mid range 30 caliber cartridges.

    • You said it yourself. The 300 BLK was never intended to be a wholesale replacement for 5.56 NATO. It’s built specifically for sbr and suppressed applications. While it may have uses beyond those, those are its wheelhouse.

  22. I have an AR that fires 223/556, with a 1×9 twist. I wanted an AR pistol for HD and general plinking, Should I go with a 10.5-11 inch 223, or a 7.5-10 inch 300. I probably won’t supress it, “no patience”. So what is the better gun for my intended use. It will stay near the BED, where my Glocks live now. I have several 9 & 45 cal with extended mags and lights /lasers on them. Is this a better idea or us it a waste of money.,I have been shooting and carrying almost 5 decades daily.

  23. I was, and still quasi-am STILL, a certified IOC or “trunk monkey” for a security firm out of faaaar Southern CA (Tijuana border AOR) even though it was from ’06 thru ’09 while my buddies joined the SOF community and went to OIF1/2 etc and so I kinda fell into that work through them and the tactical and medical courses I required certification in to do PSD work, yet now they only call me for “terp work” once every blue moon…Yeah… BUT, the fun part of not being a veteran was that even though you don’t get “thanked for your service” at every Denny’s stop, you still get trained up THAT MUCH HARDER by your instructors at each course like SOTIC, SIG Academy, etc (that’s how i ended up living here in GA/SC area by Savannah).
    What i mean to say is that the 300 BLK we used at SIG’s courses didn’t impress me outside of punching power. They had the Mike Tyson knockdown, and when subsonic, were ingenius rounds….really they were. But outside of a few ISR (integrally suppressed) rifles we had on hand to try out from POF USA, Wilson Combat-customs, etc, the problems became evident in re-indexing your next shot because, no matter what people say, 300 BLK still got just a WEEEEEE BIT of recoil. Me? I started recently (not sure how legal this is, my old man gets it for me because he thinks it’s great) getting what the US Army is about to start using which were about 500-1000 rounds of heavy grain M885A1 for my tortured DPMS AR, which despite the low price, they ARE rugged. And, yeah, I’ll say it…EASILY AS gnarly durable as the HK 416C and Mk 16/17s we see our mentors using while showing us how to do breach’n’clears on constantly changing enclosed battlespaces provided to us by the generous DoD and DoJ (only because of L-3’s contract to assist Mexico’s MoD–their DoD–with their communications networks etc, which I’m sure we got a handle on their SIGINT pretty fast afterwards).

    Now, as I knew two actually usable Spanish dialects in a few weirder mountain areas near Monterrey by the Sierra Madre mnts etc and, not just that, but we were taught the asymmetrics and atmospherics from freshly DD214’d former ODA types when in the mountain Mexicans/Indians’ turf etc, you watched your six harder because they looked at us “wetos” or “gringolitos”, only there to protect other local politicians they didn’t like to begin with, and to add a bit of salt on the remark to sting a bit extra worse too…They’ve literally nearly killed our boys on more than a half dozen occasions, why? Because they were worse than ANY Juarez crazies on meth that would threaten you. BUT, HOWEVER, WHEN IT CAME TO HARDWARE, IT WAS TOTALLY DIFFERENT AS NEW PLATFORMS WERE BEING PUT OUT BY THE DOZENS FROM ALL THE TOP MANUFACTURERS. We had the first DDM4s/Mk 18 SBRs, also had the first iteration of the CSASS (Mk 11 Mod 0 if i recall correctly) and even a shorter version, the KAC SR-15. I had my jealous face on, looking at the SR-15 carbine’s length and ridiculously bad ass, legendary KAC unsung hero-level accuracy with the right ammo, and then there was me with my DPMS Panther with a Gemtech shorty–short suppressor with slightly less decibel killin’ the others, i.e 139 db for most of it’s use until it sh-t the bed on me).
    OUT OF EVERYTHING I USED, I WOULD’VE GIVEN ANYTHING FOR A HYBRID MULTI-CAL AR. I know how impossible it seems to some (or unfeasible/unreasonable/etc), is that you’d need an AR like the older Bushmaster ACR and these new SIG MCX AR platforms to have the interchangeability w/ calibers but I’d love to have .308 AND the .223/5.56mm as a choice (which means same for the 300 BLK that you’d have access to as well right??? I mean please correct me if my dream AR is impossible, but that’s how I felt when I saw the Massad on Futureweapons get basically turned into ANY known assault rifle barrel length (sniper/assaulter/etc) with multible calibers that even included the Soviet 7.62×39!! Now, I don’t like 6.8SPC (been there, done it) all that much as it’s spin drift and tendency to have several diff type 1/2/3 etc malfunctions at the worst times. SAME problems we heard about, AT THE TIME, went for guys trying to feed 300 BLK or AAC into their 5.56mm and/or .223 cal ARs. THAT was what I understood, for all i know, it’s the most popular rnd gaining hype next to .338 Lapua, 300 AAC, or 6.5 Creedmoor at this point after all these years. I just stuck with my crappy, beat up, urban grey and tan painted DPMS AR with 77gr Black Hills as the only round I used EVER. No $$ limits when it comes to being alive another day, as opposed to putting green tips by the half dozen into a crazed Mexican corrupt Federales unit with body armor.

    Plus, I had taken classes AND was raised by a babysitter who spoke two dialects anyways, plus I had the slang etc. I stopped to go back to teaching music (yeah I know…but it’s that + Walgreens for work that gets me by these days, outside of the really pathetically low $$$ and occasional iTunes check from touring in this unsigned Volcom Skateboards-backed band that many years back tried to get onto Stone Entertainment).
    During this time, *things got bad, like really bad and I was on opiates for wounds I took over the years etc that I never wanted to get hooked on and the docs lie and say to not worry yadda yadda yadda*. I end up doing operations with TITANGROUP/L-3 Comm and Triple Canopy down below the border liaising with Mex LE in diff “trouble areas” as our principal would call it. And we’d get in TICs!! *It was gruesome, ridiculously nuts, and straight up told to me by our other guys who were former JSOC types from TF Green etc that MEXICO was worse in terms of random ambushes etc than Somalia, Iraq, and Af/Pak AOs combined!!!* So imagine a dude saying that to you with the big tactical beard and tat sleeves etc along with being somehow over 6’11” lol jk…No most were small dudes just stocky…Point is, they had these Aero AR-15s and AR-10 SBRs that I wished we could just combine into ONE single two-part upper series ARs. You just drop the needed parts, magazine parts, barrels, etc and have it all ready as possible before trying to change it out….But I’m not an SME on ARs and for all I know, I’m saying something as stupid as “I wish I could ride into battle with Vikings on Unicorns!!!!!!!” w/ just the same amount of high excitement. PLEASE CORRECT ME IF THEY CAN’T DO IT. Otherwise….
    Point is, I tried a .300 BLK first few months (a POF USA ISR that I had customized to my specs in terms of a full-set of BCM furniture, handguard+ AFG+a $70 UGT Red Dot w/ NO expensive EOTech 3x behind it lol….Smart right? Especially as those Mexi hot lead bumblebees zipped past me on more than a few occasions.

    LONG STORY SHORT—I say easiest move IS ABSOLUTELY the M885A1 and all the new variants for the 7.62 version ALSO… instead of trying to go 300 BLK on anything standard issue for priv sec firms like mine, as elite as it’s members were and had “big boys rules” type choices for their choices in long guns. BUT, as luck would have it, I move to SC/GA area (like literally, straddling the border by Savannah and meet guys from Daniels Defense through my old buddies who hooked us up together w/ some Red Bull dudes on a Wounded Warrior Project gig and, if interested, please don’t allow yourself to hesitate to contact me about it as we have a broadcasted show on LIVELY.TV now)

  24. You use the most piss poor round you can find, even Silver Bear has better velocity, to try and prove your point. Waste of time reading this drivel.

  25. My question is if there are no limitations which caliber would the Author choose, which barrel length and which manufacture.
    Thank you your articles have been informative to me.

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