300 Blackout compared to 7.62x39, what is the deal?

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Robert Nicholson

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Apparently 300 Blackout is designed to work well in the AR platform, which the 7.62x39 does not.

How come? What do they mean? Both cartridges are about the same size and same configuration, what's up?:confused:
 
That was my understanding as well. 300 blackout was designed so it works within the parameters of the AR platform and magazines.

Cheers,

From Wiki-The project's goals were:

Create a reliable compact .30-cal solution for AR platform
Use existing inventory magazines while retaining their full capacity
Create the optimal platform for sound and flash suppressed fire
Create compatible supersonic ammo that matches 7.62×39mm ballistics
Provide the ability to penetrate barriers with high-mass projectiles
Provide all capabilities in a shorter, lightweight, durable, and low recoiling package

Meeting these goals allowed the development team to negate many of the perceived drawbacks inherent to other large caliber cartridges when used in the M4 platform. Colt Firearms and other arms makers had previously chambered AR-pattern rifles and carbines in various .30 caliber rounds but several issues were encountered. In the case of the 7.62×39mm, its relatively severe case angle caused feeding issues unless specially modified AK-47 magazines were used, and even then results were less than outstanding.

link: https://en.m.wikipedia.org/wiki/300_AAC_Blackout_(7.62×35mm)
 
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The 300 BLK was designed off of a 5.56x45 cartridge. Meaning that the bolt and magazine stay the same. The 7.62x39 needs a larger bolt face and different magazine dimensions, which causes the issues you see running it in an AR platform.
 
When the 7.62x39 works in the SKS and AK platforms, why would anyone try to make it work in a AR? If you wanted a AR with more punch 300blk/whisper is available. About the only advantage i could see is availability of cheap surplus ammo, but cheap 223 is available. Once you have a suitable amount of brass, dies, projectile; reloading for the Blackout is exactly the same as any other caliber.
 
7.62x39 is a lot cheaper and a little bit more accurate then .300 blk, I would go with it over .300 blk.
However a lot more company's are starting to offer stuff to reload 7.62x39 now

The big problem with 7.62x39 AR-15's is light primer strikes when dealing with Berdan primed ammo, which can be fixed by replacing or shaving the base of the firing pin so it will protrude more and using heavier hammer springs. Other issue is with failures to feed from, due to the feeding ramp being to small, which again is an easy fix.
 
Hermid said:
7.62x39 is a lot cheaper and a little bit more accurate then .300 blk, I would go with it over .300 blk.
However a lot more company's are starting to offer stuff to reload 7.62x39 now
Click to expand...

What you're saying is quite opposite article on Wiki:
In comparison with 7.62×39mm rounds, 300 BLK rounds with varying loads have a better ballistic coefficient and more energy out of similar length barrels. The 300 BLK also has advantage over the AK-47 because of its ability to use subsonic ammunition.
Click to expand...
 
Just wanted to add that high volume reloading requires some expensive gear if you want to do it in a reasonable amount of time. You can purchase 7.62X39 for about the same price as you can reload 300 Blk.

If you are going to shoot it ALOT there's only 3 practical chambering's for the AR-15, .233/5.56, 7.62X39, and 9mm Para.

If I'm not mistaken the 300 Blk/Whisper is based on the 221 Fireball, making brass from .223 would be a pain in the rear.
 
Horilka said:
What you're saying is quite opposite article on Wiki:
Click to expand...

Not really, the Russian Case is the parent of what many claim to be the most accurate cartridge available, the 6 PPC. The 7.62X39 is likely at least the equal of the Black Out as far as shooting groups goes, B.C. and Energy don't make a rifle accurate.
 
The 7.62x39 has much more case taper than the 300BO. x39 works very well in typical banana (AK type) mags but not so much in AR style mags (much straighter mag body). Because the 300BO is designed off the .222/.223 case it feeds better when used in a AR platform.
 
redshooter said:
Not really, the Russian Case is the parent of what many claim to be the most accurate cartridge available, the 6 PPC. The 7.62X39 is likely at least the equal of the Black Out as far as shooting groups goes, B.C. and Energy don't make a rifle accurate.
Click to expand...

To be more specific (and at the risk of splitting hairs), the PPCs are based on 220 Russian, which is itself based on 7.62x39.
The most notable point to the differentiation is the fact the 220 Russian and the PPCs that followed retained the use of small rifle primers, a trait that the inventors and shooters argue forms one of the reasons these cartridges have inherent accuracy.

However way you slice it, guys running an AR for accuracy are probably going to pick 7.62x39 dead last. It is a fun intermediate cartridge with cheap, abundant and not-so-accurate military surplus ammo available.
The buy-in for an AR in x39 is that cheap surplus ammo, whereas with blackout it is all about the performance of the cartridge with suppressors - why guys use them in Canada is questionable, but I guess they just want to be 'that guy' with something different. Neither of these rounds can practically perform to the accuracy of .223/5.56 at distances out to 5-600m, so they fill niche roles.
 
Nothing wrong with splitting hairs...more info is pretty much always better.

7.62X39 doesn't exactly have a plethora of match projectiles either. Some nice brass though...
 
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