One of the reasons for the AR-15's ever growing popularity isthe variety of cartridges it can chambe...

1. 300 Blackout vs. 7.62x39mm: how does this this American
cartridge stack up against the Soviet classic? It may surprise
you to hear there's not much gap between the two.
One of the reasons for the AR-15's ever growing popularity is
the variety of cartridges it can chamber. It was a different world 20
years ago when you could only choose between the 5.56x45mm and a handful
of wildcats. But those days are gone, and today shooters can choose from
a host of interesting factory-loaded cartridges.
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Center-fire offerings run from 5.45x39mm all the way up to .50
Beowulf. The concept of the AR-15 being nothing more than a "poodle
shooter" seems silly today. Chambered for the right cartridge, the
little Black Rifle is capable of taking any game animal in North
America. Every new cartridge to appear simply broadens the AR's
appeal.
It's interesting to note, though, that Americans remain in
love with their .30 cals. It seems almost ingrained in our culture.
While other bullet diameters may have certain advantages, the .30 cal.
remains an American favorite.
Unfortunately, an outstanding factory-loaded .30 cal. cartridge
that interfaces well with the AR-15 design has been missing. Until
recently the best option for a factory loaded .30 cal. cartridge was the
7.62x39mm. While this Soviet-era intermediate cartridge is a truly
excellent design, it does have its drawbacks when transplanted into an
AR-15.

2. So the introduction of the 300 AAC Blackout stimulated a great deal
of interest among both shooters and hunters. The question I had was how
does this new offering stack up against the well proven 1940s-vintage
7.62x39mm?
Hugely popular around the world, the 7.62x39mm is the yardstick
against which all other intermediate cartridges are measured. Designed
originally for military use, it easily made the transition to a sporting
cartridge. Today a wide variety of loads are offered in this caliber for
hunting, recreational shooting and personal protection.
In Russia and many other countries, it is a popular hunting
cartridge and used to harvest a wide variety of game. Here in the USA it
is very popular for recreational shooting and personal protection. Many
also appreciate its capabilities as a short range deer cartridge,
especially in heavily wooded terrain.
The 7.62x39mm was developed by a team of Soviet engineers in the
early 1940s and type qualified in 1943. Without a doubt a number of
German intermediate cartridges influenced the design. The goal of the
design team was to develop a modern intermediate cartridge well suited
for use in autoloading weapons with acceptable penetration, terminal
performance and exterior ballistics out to approximately 400 meters.
Their work led to a cartridge with an overall length of 2.205
inches (56mm) and a case length of 1.524 inches. (38.7mm). Base diameter
is .447" (11.35mm) which tapers noticeably to a shoulder diameter
of .396" (10.07mm). Rim thickness is an admirable .059"
(1.5mm). The short case was loaded with a projectile .312" (7.62mm)
in diameter weighing 123 grains. This original M43 load featured a full

3. metal jacket projectile with a boattail to improve its exterior
ballistics. It also featured a mild steel core to improve penetration of
commonly encountered intermediate barriers. Muzzle velocity from a
16-inch barrel is approximately 2330 fps.
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The 7.62x39mm was initially fielded in the 7.62mm RPD (Ruchnoy
Pulemyot Degtyaryova= hand-held machine gun of Degtyaryov) squad
automatic weapon and SKS-45 (1945=Samozaryadnyj Karabin sistemy
Simonova, 1945= Self-loading Carbine of (the) Simonov system, 1945).
However it is most famous for its use in the AK-47 (Avtomat
Kalashnikova) series of assault rifles. Here in the USA, though the
7.62x39mm has not only been available in semi-automatic Kalashnikovs,
RPDs and SKS-45s but also in other semi-automatic designs as well as
bolt-action sporting rifles.
A number of American companies, including Colt, have offered AR-15
type rifles chambered in 7.62x39mm. While this cartridge design is well
proven and developed on well-grounded military requirements, it is not
ideally suited for use in the M16/AR-15 platform, thanks to the amount
of taper on the cartridge case in relation to the height of the
AR's magazine well.
The combination creates difficulties when designing a reliable
high-capacity magazine and leads to feeding problems. While some high
capacity magazines work flawlessly in some rifles, others are
problematic. In addition, firing pin modifications are often required to
ensure reliable ignition of Mil-Spec primers. Lastly, some do not like
the fact that ARs in this caliber require a caliber-specific bolt and

4. magazine. You can't simply stuff 7.62x39mm rounds into a 5.56x45mm
caliber magazine. Instead you must hunt for caliber-specific magazines.
On the plus side, ARs in 7.62x39mm are generally noticeably more
accurate than a standard 7.62x39mm Kalashnikov. Plus factory fresh
7.62x39mm steel case ammunition is very economical to shoot and readily
available.
Today a number of companies offer loads beyond the traditional FMJ
fodder. Without a doubt though, Wolf Performance Ammunition remains the
leader when it comes to this caliber. In addition to traditional FMJ
loads, they also offer hollow-points and soft-points.
Their soft-point loads in particular provided respectable
performance when tested in 10% ordnance gelatin. However a number of
domestic ammunition manufacturers also offer high quality expanding
loads which improve the terminal performance of this old Soviet
cartridge. American Eagle, Doubletap, Cor-Bon, Federal, Hornady and
Winchester all offer loads in this caliber. Not to be forgotten is Engel
Ballistic Research's 220-grain Jack-hammer subsonic load. Developed
specifically for use in the AR it provides reliable cycling with
impressive subsonic performance.
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How does the 300 AAC Blackout compare? When all things are
considered, quite well actually. For those of you unfamiliar with this
interesting cartridge let's take a quick look at it. No one will
say that the concept is new.
While most will point to the .300/.221 Fireball I will put forward
that the concept is considerably older. Rummaging about through old

5. dusty books I was surprised to find a similar French military design
called the 8x35mmSR. Dating back to 1917 and the First World War, it was
intended for use in the selective-fire Carabine Mitrailleuse 1918
Ribeyrolle (Machine Carbine 1918).
The cartridge was based upon an existing design then in French
service, the .351 Winchester Self-Loading. This was merely necked down
to accept a standard French 198-grain 8mm Balle D solid brass
projectile. An unconventional design, it featured a base diameter of
.380" and a 35mm (1.37 inches) case length.
The 1918 Ribeyrolle was fed from 25-round detachable box magazines
and, with its short 17-inch barrel, well suited to trench clearing. It
would have been very controllable on full-automatic and would have
likely left its mark were it not for the end of the war.
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While the similarities between the 8x35mmSR and 300 BLK (7.62x35mm)
are striking, most will point to the much more familiar .300/.221
Fireball wildcat and JD Jones' .300 Whisper. It's obvious the
300 BLK was based upon these cartridges. The 300 BLK came about after
Robert Silvers, the Research and Development Director of Advanced
Armament Corp. (AAC), was contacted by a government customer in 2010.
The customer had a requirement for this concept and requested AAC to
produce firearms with Remington Defense manufacturing .300/.221 Fireball
type ammunition. This request would lead directly to Silvers developing
what we know today as the 300 Blackout cartridge.
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6. Since Remington is a member of SAAMI and only produces
SAAMI-approved ammunition, this created some issues. The .300 Whisper is
a proprietary name which requires licensing, and SAAMI does not accept
trademarked names. So that was out. Plus due to its wildcat status there
were a number of .300/.221 Fireball chambers.
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If they picked that name, Remington would have had to clear
compatibility with all the existing chambers. Doing so would have
limited velocity potential because they would have to pressure-test the
ammo in the tightest one.
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The goals of the project were fairly straightforward:
1. Create a reliable .30 cal. cartridge compatible with the AR
platform.
2. Create the optimal platform for sound -and flash suppressed
fire.
3. Develop supersonic ammunition to match 7.62x39mm ballistics.
4. Provide the ability to penetrate commonly encountered barriers.
5. Utilize existing M16 magazines at their full capacity.
6. Encapsulate these capabilities in a light-weight, low recoiling
yet durable package.
During a conversation I had with Silvers, he commented; "300
AAC Blackout was designed to be the most powerful way to shoot .30 cal.
from an AR-15 while remaining compatible with normal 30-round magazines.
A fresh name was needed so that we could design the chamber with the
exact specs we thought best.

7. 300 AAC Blackout is a name both consistent with full-power ammo,
but yet stealthy at the same time. For 300 AAC Blackout, we went back to
the official Remington .221 Fireball drawing and used the exact
dimensions from the rear, while doing the front portion in an optimal
way.
We picked a longer throat than in some Whisper chambers to allow a
Sierra 220 MatchKing to be loaded to full magazine length while being
.010" from the rifling. That keeps pressure down, and allows for
full power ammo to be loaded hotter for more velocity."
So what does all this mean? Simply that the 300 BLK was designed
from the ground up to utilize standard 5.56x45mm AR-15 bolts and
magazines. This means there is no need to hunt for a different bolt or
different magazines. It also means that to convert an existing 5.56x45mm
AR-15 to 300 BLK only requires a simple barrel swap. That's it;
nothing else needs to be changed except your muzzle device. This is a
big deal for many shooters sitting on a pile of 5.56x45mm magazines.
There's no need for expensive proprietary magazines.
It also means the cartridge and chamber dimensions were
specifically optimized for use with both super- and subsonic ammunition.
Sound suppressors continue to grow in popularity here in the USA.
Hearing loss is a real concern for many shooters, your author included.
Sound suppressors make shooting much more pleasant and enjoyable.
With the 300 BLK you can enjoy running both supersonic and subsonic
ammunition through a sound suppressor. Not only that, but the cartridge
works extremely well in ultra-short barrels. So if you don't mind
putting the paperwork through, you can have an ultra-short and

8. suppressed 300 BLK AR carbine.
What about if you do mind putting paperwork through'? Is there
still any reason to consider the 300 ELK? Absolutely! The vast majority
of American shooters and hunters will select 16+ inch barrels. The 300
BLK is right at home in lengths like this and, properly built, will
allow you to seamlessly switch between supersonic and subsonic
ammunition.
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Now please keep in mind that when it comes to sheer brute
horsepower, the 300 BLK cannot quite match the 7.62x39mm. The 300
BLK's case capacity is simply less than the fatter 7.62x39mm, so it
cannot match the Russian cartridge's muzzle velocities with equal
weight projectiles.
However, for the most part, the 7.62x39mm is saddled with
inefficient projectiles, many designed decades ago. This means the 300
BLK can match or actually improve upon the downrange performance of the
7.62x39mm through the use of more efficient modern projectiles. However
this depends upon individual loads.
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300 BLK supersonic loads will drive 110-to 125-grain bullets at a
claimed velocity of 2250 to 2350 fps. So advertised muzzle velocity is
about 100 fps slower with equal weight bullets fired from equal length
barrels.
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With the 300 BLK, a hunter or shooter can also select from a
variety of subsonic loads. These range in weight from 200 to 240+

9. grains. Subsonic loads are simply those which drive their projectile at
less than the speed of sound. The speed of sound in dry air at
68[degrees] F is 1126 fps. Heavy efficient projectiles with high
ballistic coefficients retain their velocity and energy well.
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So despite very low initial velocity a 200+ grain .30 cal. subsonic
load can provide acceptable performance on medium-size game. Better
still it can do this, when teamed with a sound suppressor, at a very
pleasant and safe noise level.
Interested to see how the 300 BLK would actually perform, I put one
of Alexander Arms' carbines to work. This was fitted with a 16-inch
stainless steel fluted barrel with a 1:8 inch twist and a carbine-length
gas system. It featured an AAC Blackout flash suppressor, M1913 gas
block and Mk10 Plus handguard.
The barrel was fitted to a flattop receiver featuring M4 feed ramps
and MPI bolt. The lower receiver sports a collapsible stock, making for
a very handy package weighing just 6.4 pounds.

10. This was compared to a Century Arms Inc. Centurion 39 Sporter in
7.62x39mm. Made in the USA on a milled receiver, this model sports a
16-inch barrel, muzzle brake, fully adjustable rear sight, lore-end and
handguard with 1913 rails, slightly longer stock and pistol grip with
finger grooves.
I began by selecting five different 7.62x39mm loads and running
them through the Centurion 39. These ranged in weight from 122 to 154
grains. Loads were selected from Wolf, Norma and PMC and included one
discontinued load, Wolf's 154-grain SP. I included this load just
to demonstrate what the 7.62x39mm could do with a heavy bullet.
Four consecutive five-shot groups were fired with each load from
the bench at 100 yards. Velocity was measured 10 feet from the muzzle
with an Oehler 35P chronograph. Also keep in mind the Centurion 39
groups were fired using iron sights, while the Alexander Arms 300 BLK
were fired with an optic. But I was less concerned with accuracy

11. compared to measuring muzzle velocity. My intent was to check to see how
actual muzzle velocities compared between the two cartridges.
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When it comes to feeding your 300 BLK, things can get just a bit
confusing. Currently, ammunition manufacturers are offering both 300
Blackout and .300 Whisper labeled loads. These look the same minus the
headstamp. So I asked Silvers about this. He stated, "Hornady makes
its .300 Whisper brass to be compatible in 300 AAC Blackout chambers.
(However) it is not guaranteed safe to use 300 AAC Blackout ammo in 300
Whisper chambers, because there may be a pressure increase if they have
a shorter throat. Think of 300 AAC Blackout as being more like 5.56mm
and .300 Whisper being more like .223 Rem. A longer throat means less
pressure, which means you can load ammo to be faster." So please
keep this in mind.
So I selected a combination of both 300 BLK and .300 Whisper loads
to run through the Alexander Arms carbine. In addition, I selected both
supersonic and subsonic loads. Bullet weights ranged from 110 to 208
grains. Blackout loads consisted of Barnes' highly regarded
110-grain TAC-TX and Remington's 115-grain CTFB and 125-grain
Accutip.
.300 Whisper loads consisted of Hornady's 110-grain V-Max,
Lehigh Defense's 140-grain Controlled Fracturing and 200-grain
Maximum Expansion and Hornady's 208-grain A-Max. Testing was
conducted the same as for the 7.62x39mm with the only difference being
the addition of an optic on the Alexander Arms carbine.

12. How did the two cartridges stack up? The results were actually
fairly interesting:
CENTURY ARMS INT. CENTURION 39 7.62X39MM
Load Bullet Muzzle Standard Average
Weight Velocity Deviation Group
(grs.) (fps) (ins.)
Wolf SP 122 2376 30 3.7
Wolf FMJ 122 2269 37 3.2
PMC SP 123 2130 27 3.8
Norma SP 125 2301 21 3.2
Wolf SP 154 2045 28 2.9
ALEXANDER ARMS 300 BLACKOUT
SUPERSONIC
Load Bullet Muzzle Standard Average
Weight Velocity Deviation Group
(grs.) (fps) (ins.)

13. Hornady 110 2350 17 1.3
V-Max
Barnes 110 2307 17 1.8
TAO-TX
Remington 115 2302 9 2.1
CTFB
Remington 125 2234 25 2
Accutip
Lehigh 140 2059 12 3.5
Defense CF
SUBSONIC
Load Bullet Muzzle Standard Average
Weight Velocity Deviation Group
(grs.) (ins.) (fps)
Lehigh 200 1183 33 2.7
Defense ME
Hornady 208 1007 3 2.1
A-Max

14. Notes: Accuracy results are averages of five 5-shot
groups fired from a rest at 100 yards. Velocity
figures are 10-shot averages recorded on an Oehler
35P chronograph placed 12 feet from the muzzle
at an ambient temperature of 85[degrees] F at 1030
feet above sea level.
While the Alexander Arms 300 BLK outshooting the Century Arms Int.
7.62x39mm Kalashnikov came as no surprise, the Centurion 39 acquitted
itself well. What surprised me was how factory 300 BLK/.300 Whisper ran
so close velocity wise to 7.62x39mm factory loads. Actually
Remington's 300 BLK 125-grain Accutip load at 2234 fps outran
PMC's 123-grain SP 7.62x39mm load running at a doggy 2130 fps.
It's also interesting to note that some loads in both calibers
failed to achieve their advertised velocities.
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The end result? While the 7.62x39mm does have an edge in muzzle
velocity with factory loads, its nothing to write home about. Regarding
accuracy? Both rifles made consistent hits firing from the prone
position on a man-sized target at 300 yards. I'd like to add that
there's a good bit of drop that needs to be taken into account when
switching from the 300 BLK/.300 Whisper supersonic loads to subsonic
ammunition.
Hornady's 208-grain A-Max load dropped 14 inches from the
supersonic zero at 100 yards. Lehigh Defense's 200-grain load was a
bit faster and only dropped 9.5 inches at 100 yards.
Punching the numbers into a JBM ballistics calculator for two loads

15. provided these results. With a corrected muzzle velocity of 2316 fps,
the 300 BLK 110-grain Barnes TAC-TX showed a muzzle energy of 1310
foot-pounds. At 100 yards it retained 2039 fps and 1015 foot-pounds, at
200 yards it retained 1783 fps and 776 foot-pounds and at 300 yards it
retained 1551 fps and 587 foot-pounds.
With a 100-yard zero it dropped 24 inches at 300 yards. In
comparison, a Lapua 7.62x39mm 123-grain FMJ at a textbook 2330 fps
generates 1482 foot-pounds. At 100 yards it retains 2012 fps and 1106
foot-pounds, at 200 yards it retained 1723 fps and 810 foot-pounds and
at 300 yards it retained 1467 fps and 588 foot-pounds. With a 100-yard
zero it dropped 26 inches at 300 yards. So exterior ballistics of the
two loads is very similar. However the Barnes 110-grain TAC-TX offers
.50 cal. expansion and more than 20 inches of penetration at 300 yards!
My thoughts? Both the 7.62x39mm and 300 BLK are very useful
cartridges. Neither are magnums, nor can they outmuscle more
powerful/efficient cartridges like the 6.5x38mm Grendel and 6.8x43mm
SPC. However, they launch .30/.31 cal. projectiles at respectable
velocity. Most American shooters and hunters fire predominantly inside
300 yards. This is the type of work these cartridges were designed for.
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With properly selected projectiles and well-placed shots both will
work on deer-sized game. Currently 7.62x39mm has a noticeably edge when
it comes to economical ammunition. However 300 BLK has a wide variety of
very modern loads available for it with state-of-the-art projectiles.
If you're interested in .30 cal. performance from your AR-15,
I'd lean towards the 300 BLK. Many companies, like Alexander Arms,

16. are getting behind it. This is a very good thing as the more industry
supports this cartridge the more loads, firearms, dies, components, data
and accessories will be available.
Brass can be made from common 5.56x45mm cartridge cases by trimming
them to 1.358 inches and simply running them through a sizing die.
Reloading data, dies and components are readily available. Is the 300
BLK right for you? Only you can answer that question. But if you'd
like a lightweight, quick-handling and accurate .30 cal. semi-auto
carbine for use inside 300 yards, I'd seriously consider it.
SOURCES
Advanced Armament Corp.
770-925-9988 / www.advanced-armament.com
Alexander Arms
540-639-8356 / www.alexanderarms.com
Century Arms, Int.
800-527-1252 / www.centuryarms.com
Hornady
800-338-3220 / www.hornady.com
Lehigh Defense
267-217-3539 / www.lehighdefense.com
Remington
800-243-9700 / www.remington.com
Wolf Performance Ammunition

17. 888-757-9653 / www.wolfammo.com
300 MC BLACKOUT
SPECIFICATIONS
Parent Case: .221 Fireball/.223 Rem.
Case type: Rimless bottleneck
Bullet diameter: .308" (7.8mm)
Neck diameter: .334" (8.5mm)
Case length: 1.368 inches (34.7mm)
Overall length: 2.26 inch max SAAMI
Primer type: Small Rifle
Maximum pressure: 55,000 psi (380 MPa)
SUGGESTED POWDERS FOR LOADING 300 MC BLACKOUT
SUPERSONIC USE
1. H110
2. W296
3. N110
SUBSONIC USE
1. A1680
2. IMR 4198
3. Reloder 7
ALEXANDER ARMS 300 BLK CARBINE
SPECIFICATIONS
Action Type: Semi-auto via direct gas with rotating bolt
Caliber: 300 ACC Blackout
Capacity: 20 -and 30-round detachable box magazine

18. Barrel: 16-inch fluted stainless steel with 1:8 inch twist
Overall Length: 36.5 inches with stock collapsed
Weight: 6.4 pounds without magazine
Stock: Synthetic 6-position collapsible
Finish: Phosphate
Trigger: 6-lb pull as measured; single-stage
Sights: None, 1913 optics rail
Price: MSRP $1,800
Manufacturer: Alexander Arms, www.alexanderarms.com, 540-639-8356
COPYRIGHT 2012 InterMedia Outdoors, Inc.
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