The 223 Remington round has been the gold standard AR-15 cartridge for well over 60 years. It has been the ammo issued to our frontline soldiers for over a generation and has seen combat on 5 continents in the hands of the U.S. Military, our NATO allies, and law enforcement officers.
However, some shooters wanted more out of their AR platform, they wanted the ability to shoot a 30-caliber bullet without switching over to the heavier AR-10 and 308 Winchester.
Enter the 300 AAC Blackout, the successful marriage of 7.62x39mm terminal ballistics with the modularity of the AR platform. Requiring only a barrel change, the 300 Blackout offers shooters the versatility to shoot 30-caliber supersonic and subsonic ammo.
But which round is superior? Does the ballistic performance of the 300 BLK warrant widespread adoption of the cartridge by the military, law enforcement, and civilians? Or does the stalwart performance of the 223 continue to dominate with its long range prowess, muzzle velocity, and stopping power?
In this article, we will compare the 223 Remington and 300 Blackout rifle cartridges so you can make a more informed decision on your next rifle purchase.
What is the Difference Between 223 and 300 Blackout?
The primary difference between 223 and 300 Blackout is the bullet diameter each rifle cartridge fires. The 223 Rem fires a 0.224” diameter bullet while the 300 BLK fires a 0.308” diameter bullet.
A Note on Nomenclature
In the context of this article, .223 Remington (223 Rem) and 5.56x45mm NATO (556 NATO) will be used interchangeably.
However, please understand that rifles chambered in 223 are different than those chambered in 5.56. It’s important to note that NATO spec ammunition should ONLY be fired from rifles chambered to NATO specifications.
You should experience zero issues shooting .223 Rem ammo in your 5.56 rifle, but not vice versa. This is due to chamber pressure differences between the .223 vs 5.56 rounds.
Bottom line: Know what round your rifle is chambered in (it’s typically engraved on the barrel or receiver of your rifle).
When comparing two rifle cartridges, it’s a good idea to analyze the cartridge specs to gain more knowledge of each.
The most obvious difference between the 300 Blackout vs 223 Rem is the bullet diameter that each rifle cartridge fires. The 223 Remington fires a 0.224” diameter bullet while the 300 BLK uses a 0.308” diameter bullet.
Both cartridges have the same overall length so they can fit in standard AR-15 mags. Since 30-caliber projectiles are considerably longer than 223, the case length and case capacity for the 300 Blackout round had to be reduced to maintain the same overall length as a 223 round.
With a reduced case capacity and considerably heavier bullet, we can expect the 300 Blackout to have lower muzzle velocity than the 223 Rem. As we can see in the ballistics tables below, standard 125 grain 300 BLK ammo has a muzzle velocity of 2,250 fps while 55 gr 223 Remington ammo will clock in at 3,240 fps.
However, what the 300 BLK lacks in muzzle velocity, it more than makes up in muzzle energy as those heavy 30-caliber bullets pack a wallop. Comparing the same two rounds as above, the 300 BLK exits the muzzle with 1,404 ft-lbs of force compared to 1,282 ft-lbs for 223.
Neither the 300 BLK nor the 223 Rem are known for having shoulder-punishing recoil. On the contrary, most shooters report having zero issues spending a whole day at the range plinking with either cartridge.
As the 300 Blackout bullet will be heavier, it will generally have higher recoil than the 223 Rem. On average over several supersonic loadings, the 300 Blackout will have 6 ft-lbs of felt recoil while the 223 Rem will impart around 4 ft-lbs of felt recoil into the shoulder.
Although the 300 BLK bullet will have 50% more recoil than the 223, this sounds a lot worse on paper than it is in real life.
Neither cartridge is difficult to handle and recoil should not be a consideration when comparing 223 vs 300 BLK as both are a joy to shoot.
Trajectory is how we quantify a bullet’s flight path as it travels downrange measured in inches of bullet drop.
Obviously, a flatter shooting cartridge is preferred for shooting longer ranges, as a shooter will require fewer adjustments to their optics to compensate for bullet drop. Having a flatter trajectory also means that a cartridge will be more forgiving of ranging mistakes.
The 223 is well known for its flat trajectory and combat effective range of over 500 yards.
Looking at the ballistics tables below, we see that a standard 55 grain bullet will experience around -27” of bullet drop at 400 yards. However, 125 grain 300 Blackout ammo will have around -55” of bullet drop at the same range.
The 223 Rem is clearly the better choice for long range shots as it has a higher muzzle velocity and flatter trajectory.
Ballistic coefficient (BC) is a measure of how well a bullet resists wind drift and air resistance. Put another way, it’s a numeric representation of how aerodynamic a bullet is. A high BC is preferred as this means the bullet will buck the wind easier.
Generally, heavy bullets will have a higher BC as it takes more force to disrupt the flight of a heavier bullet than a lighter one. Ballistic coefficient varies from bullet to bullet based on design, weight, and other factors that are beyond the scope of this article.
The 300 BLK will generally have a higher ballistic coefficient than the 223 Rem. This is because the .300 Blackout fires a 30-caliber bullet that can be 3x heavier (or more) than 223 bullets. All that added weight makes it more resistant to wind drift.
Some of the heavier subsonic bullets for 300 Blackout have extremely high BC, such as the 208 gr Hornady A-Max, at 0.648. However, 300 BLK ammo has an average BC around 0.35. This is in stark contrast to the 223 which has an average BC of around 0.248.
Sectional Density (SD) is the measure of how well a bullet penetrates a target. This is extremely important when hunting big and medium sized game, as you need a bullet that can punch through thick hide, bone, and sinew.
Sectional density is calculated by comparing the bullet weight and the bullet diameter. The higher the SD the deeper the bullet will penetrate into the target. This is a simplified view of penetration as there are other factors to consider, such as bullet expansion and velocity.
Bullet jacket design also plays a part in penetration, as a bullet designed to expand like a soft point (SP), ballistic tip, or jacketed hollow point (JHP) will naturally penetrate less than a full metal jacket (FMJ).
Overall, as the 300 Blackout fires a heavier bullet, it has higher sectional density than a 223. The 300 BLK has an average sectional density of approximately 0.21, while the 223 Rem has an average sectional density of 0.181.
When it comes to small game hunting, it is hard to beat the 5.56mm NATO/223 Remington. With a long history in the varmint hunting arena, the 223 Rem has an established track record of being the bane of coyotes, foxes, groundhogs, prairie dogs, and other small game across North America.
However, anything larger than that and the 223 simply does not have the terminal performance to ethically claim medium to large game such as whitetail. Furthermore, many states do not allow the use of 0.224” diameter bullets for hunting deer or antelope.
Here is where the .300 Blackout steps up to the plate and those spectacular terminal ballistics come into play.
With its larger, 30-caliber bullet, a supersonic 300 BLK round is more than enough to take down a whitetail or feral hog within 200 yards. Quick follow-up shots with a 300 Blackout are relatively easy with its integration in the AR platform, ensuring you fill your bag limit.
A quick note on subsonic ammunition and hunting – it is NOT recommended to use subsonic ammo for hunting medium game. The subsonic rounds simply do not have the muzzle velocity needed for reliable expansion at hunting ranges to be effective and ethical at harvesting game. Therefore, make sure you are using supersonic .300 Blackout ammo when hunting.
Suppressor and SBR Integration
One of the key attributes of the 300 AAC Blackout is its ability to be effectively suppressed in a short barrel AR-15 (or M4 carbine for our military).
In close quarters battle (CQB) like our soldiers experienced in the urban setting of Iraq, having a maneuverable rifle with a short barrel and a suppressor to reduce the rifle report is critical for maintaining situational awareness and communication during a firefight indoors.
As sound will echo off interior walls, a rifle fired indoors will be considerably louder than what is experienced shooting outdoors, necessitating the use of suppressor.
Suppressors work by reducing the sound of the gunpowder igniting during the firing sequence. However, the sonic crack of the bullet breaking the sound barrier cannot be reduced by a suppressor.
Most rifle cartridges are fired at supersonic speeds, meaning faster than 1,125 fps. Of course, a 223 Rem can be suppressed, and many shooters do it, however there are some drawbacks to suppressing an AR-15 in 223.
The biggest issue that many shooters report is gas blowback from the gas system on the AR rifle system.
During normal firing, there should not be any issues with excess gas as the recoil system in the AR-15 is designed to handle this. However, when a suppressor is added, extra gasses trapped in the silencer get directed back through the gas system into the chamber and gas port.
This will often cause gas to be forced back into the face of the shooter, making it rather uncomfortable to fire 223 suppressed without specialized parts such as a Gas Buster charging handle.
Advanced Armament Corporation had this in mind when they developed the .300 Blackout to be an ideal option for suppression as well as working in an SBR.
Subsonic rounds for 300 BLK still have spectacular terminal ballistics and will experience a complete powder burn in a 9-inch barrel. Compare that to the required 12-inch barrel needed for a complete powder burn for 223 Rem.
Now you could argue that you can still shoot a 5.56 in a barrel below 12 inches, and that’s true that you can. However, all that unburnt powder will create a lovely fireball coming out of your barrel which is not the best for use in CQB. Furthermore, you will lose muzzle velocity due to an incomplete powder burn, reducing the ballistic performance of the round.
Now if fireballs are your thing, then by all means go for it! But if you are looking for a compact, maneuverable, suppressed SBR then a 9-inch barrel 300 Blackout is hard to beat.
When it comes to home defense, both the 300 Blackout and the 223 Rem/5.56 NATO have some merit.
Based on sectional density, the 223 is the better choice in an urban environment as it will over penetrate less than the .300 Blackout. And in an apartment or housing edition, you do NOT want your bullets to over penetrate.
However, if you want maximum stopping power, it is hard to beat a 30-round magazine full of 220 grain subsonic 300 Blackout ammo raining righteous vengeance out of a suppressed SBR. This rifle would be completely hearing safe (no need for ear protection) and would deliver a lot of kinetic energy to the bad guy, just at the cost of potential overpenetration.
Some shooters suggest that handguns might be a better option when it comes to self-defense, as rifle rounds tend to over penetrate.
A 45 ACP is somewhat comparable to 300 BLK as it fires a subsonic, 230 grain bullet. The 45 ACP will be packing approximately 350 ft-lbs of energy at the muzzle. Compare that to the 220 grain weight bullet fired from the 300 BLK with a muzzle energy of 480 ft-lbs, that’s over 100 ft-lbs more!
There’s no doubt that using a handgun for self-defense has some merit and many will take this option to attempt to mitigate over penetration. However, I find it difficult to pass up on the terminal ballistics and 30 round capacity of subsonic 220 gr 300 Blackout ammo slung from a suppressed SBR, AR pistol, or Sig MCX.
Ammo and Rifle Cost/Availability
The 223 Remington is one of the most plentiful centerfire rifle cartridges available in North America. You can find it virtually everywhere as shooting ranges, gun stores, and sporting good stores will all have plenty of options available.
Furthermore, 223 Rem is considered extremely affordable, and you can spend a long time at the range without hurting your wallet too much. On average, FMJ ammo will run you around $0.60/round and premium hunting ammo will cost about $1.50/round and up.
Comparatively, the 300 BLK round is a bit more costly to shoot as it has not been on the market as long. Standard FMJ 300 Blackout ammo will cost you nearly $1/round with hunting ammo costing closer to $2/round.
The main reason for the difference in cost is due to less manufacturers offering 300 Blackout ammo as it is a newer round.
Although there might be less sources of 300 BLK factory loads, one benefit is that any standard AR-15 in 223 can be converted to 300 Blackout with a simple barrel change.
However, if an AR-15 doesn’t trip your trigger, there are other options available.
Ruger recently released their Mini-14 Tactical, which is a 300 BLK offering in their long-standing and reliable Mini-14 rifle platform. If a bolt action rifle is what you’re after, then Savage, Remington, Ruger, and Mossberg all have offerings in 300 BLK.
For 223, the world is your oyster when it comes to rifles as virtually every rifle manufacturer has a 223 Remington option. You can purchase bolt action rifles, semi-automatic rifles, as well as single-shot options.
Dedicated 300 BLK AR platform rifles will generally fetch a slightly higher price than your run-of-the-mill 5.56 NATO/223 Rem AR-15. However, as conversions are so simple, a dedicated 300 BLK upper receiver or rifle is not needed like it is for 6.5 Grendel or 6.8 SPC. Just make sure you don’t get your 223 Rem and 300 BLK magazines mixed up!
Reloading for the 223 Remington and 300 Blackout are a joy and offer the handloader the option of making custom ammo to their own specs.
However, the real benefit of reloading both cartridges is that 223 brass can be converted to 300 BLK by trimming the case and necking up the case mouth to accept a 0.308” diameter bullet.
This makes finding reloadable 300 Blackout cases simpler as 223 Rem brass is cheap and easy to come by.
The other benefit of the 300 Blackout round is that it shares the same bullets as 308 Winchester, 30-06 Springfield, and 300 Win Mag. This means that you can purchase your projectiles in bulk and save when reloading for multiple 30-caliber rifle cartridges.
Virtually every bullet manufacturer like Hornady, Barnes, Federal, Nosler, and Sierra have plenty of different bullet profiles for both 0.308” and 0.224”. This allows anyone who enjoys reloading a lot of flexibility in terms of components and tailoring your perfect handloads.
A Brief History of 300 Blackout
The development of the 300 AAC Blackout (designated 300 BLK by SAAMI) rifle cartridge began in 2010 when Robert Silvers of the Advanced Armament Corporation (which was later acquired by Remington) was approached by a member of the US Military “dark ops” community.
Some special forces units were unhappy with the stopping power that the 5.56 NATO and the 9mm (used in several SMGs) offered during close range engagements and he wanted something that had more “oomph”. Something along the lines of the 7.62x39mm.
However, there were some other requirements that this customer required as well:
- The cartridge case head must be the same as 5.56mm NATO so a bolt change was not needed
- It had to shoot 30 caliber projectiles and mimic the terminal performance of the 7.62x39
- The new rifle cartridge needed to be compatible with short barrel rifles (SBR, barrels under 16”) and be completely functional with a suppressor/silencer
- Supersonic and subsonic ammo needed to be available and functional
- The rounds needed to fit into STANAG standard AR-pattern mags and maintain their 30-round capacity
Integrating new calibers into the AR-15 platform is nothing new to the shooting community. The 6.8 Remington Special Purpose Cartridge (SPC) and 6.5 Grendel are two examples that were mildly successful; however, they both required a new bolt and did not maintain the 30-round capacity requirement.
Simply modifying a M4 to fire 7.62x39mm was not an option either as the severe case taper causes multiple chambering issues using standard M4 mags. This is why you see such extreme curvature in AK-47 magazines.
A new cartridge had to be developed and the 300 Whisper, pioneered by JD Jones, was selected as the parent case. Since the 300 Whisper was a wildcat cartridge, and therefore could not simply be adopted for military use as it was not SAAMI standardized.
The new round was called the 300 AAC Blackout (300 BLK or 300 Blackout) and was approved by SAAMI on January 17, 2011.
300 BLK ammo can be broken down into two different bullet weights, 200+ grain subsonic and 110 to 125 grain supersonic.
Supersonic ammo, typically firing a 125 grain bullet, will have a muzzle velocity of approximately 2250 fps and have a muzzle energy of around 1404 ft-lbs. Industry standards list the effective range of the supersonic 125 grain bullet loadings to be 500 yards.
In contrast, subsonic loads will fire a 220 grain bullet and have a muzzle velocity of around 1000 fps and a muzzle energy of 488 ft-lbs with an effective range of 200 yards.
These two popular loadings really illustrate the versatility of 300 BLK ammo. With a simple magazine change, a shooter can switch from supersonic ammunition and long-range engagements to subsonic ammunition for short range combat.
Furthermore, the 300 BLK was designed specifically to experience a full powder burn when being fired in a 9” short barrel rifle (SBR), preferably with a suppressor/silencer.
To read more about the 300 Blackout, check out the full history of the cartridge on our 300 Blackout history page.
A Brief History of 223 Remington
Development of the 223 Rem rifle round began in 1957 and the final design was submitted by Remington Arms to the Sporting Arms and Ammunition Manufacturers’ Institute (SAAMI) in 1962.
The development of the 223 Remington cartridge was a joint operation organized by the U.S. Continental Army Command between Fairchild Industries, Remington Arms, and Eugene Stoner of Armalite, using the 222 Remington as a parent cartridge.
The 222 Remington case was elongated 0.06” and the neck was shortened. These changes allowed for the new 223 Remington ammunition to have a 20% larger powder charge than its progenitor.
Eugene Stoner was the primary inventor of the AR-10 rifle (chambered in 7.62x51 NATO), which he was invited to scale down to accommodate the new .223 Rem cartridge.
The resulting rifle that the military accepted was the M16, the civilian version being the AR-15. Since adoption, the AR-15 carbine has become the most popular sporting rifle in US history.
With its lightweight and low recoil, the M16 is an ideal platform for full auto fire and the ammo is considerably lighter than its 308 Winchester counterpart. This allows soldiers to carry more ammo into battle for the same weight, meaning they can stay in the fight longer without impeding their mobility.
Since then, the M16 and the shorter barrel length M4 Carbine have become a ubiquitous symbol of American military prowess across the globe.
The original 223 Rem mil-spec ammo that the U.S. Military adopted was named M193, which fired a 55 gr full metal jacket (FMJ) bullet at a muzzle velocity of 3240 FPS with a muzzle energy of 1282 foot-pounds.
The new 223 Remington cartridge had sufficient long range capability out to 500 yards while maintaining accuracy and offers bullet weights between 35 and 77 grains.
The 223 Rem was released to the civilian market one year before adoption by the U.S. Army, and varmint hunters enjoyed the new cartridge’s low recoil, extreme accuracy, and lower pressure.
It was not long before all the major firearm manufacturers offered semi-auto and bolt action rifle in the new 223 Remington cartridge.
To read more about the 223 Remington, check out the full history of the cartridge on our 223 Remington history page.
Final Shots: 300 Blackout vs 223
The .300 AAC Blackout is a hard-hitting 30-caliber upgrade to the AR platform that mimics the terminal ballistics of the Russian 7.62x39 and adds new levels of versatility to the rifle. The ability to change between supersonic rounds for longer shots and subsonic ammo for close range work with only a magazine change adds a level of flexibility not seen with the 223 Remington.
The innovative design of the 300 Blackout allows it to reach its full potential within a 9-inch barrel and performs best when suppressed, providing the shooter with a compact, quiet, powerful SBR with phenomenal stopping power.
The 223 Remington is a combat-proven, high velocity round that has served the U.S. Military for over 60 years. Its reliability, ability to shoot longer ranges, and low cost of acquisition make it an amazing choice for plinking, self-defense, and the preservation of liberty.
Which is best for you? That will depend primarily on what you are looking for from your AR-15. The default answer is to have both, and since a full conversion can be achieved by a simple upper receiver swap, this makes the concept much more palatable to your wallet.
Both rifle cartridges will serve you well in your shooting needs and will be more than adequate in any home defense situation.
However, if cost is a serious concern, then the 223 Remington is clearly the superior choice as there are plentiful and less expensive rifle and ammo options available.
But if cost is of no concern, then pick whichever cartridge speaks to your needs the most and hit the range…You won’t be disappointed with either!
Continue reading 300 Blackout vs 223: Getting the Most Out Of the AR-15 on Ammo.com for comparative ballistic data!