Posted on 11/19/2019 5:57:56 AM PST by Black_Rifle_Gunsmith
The 300 Blackout AR-15 Build Guide
I've had questions come through from a builder or two about 300 Blackout and its compatibility with existing build kits, parts, and the AR-15 platform. This is a dual-purpose round originally developed for the U.S Military's M4 platform by request of overseas operators. Advanced Armament Corp. (AAC) developed the round for approval by SAAMI in 2011. 300 BLK provides ballistic performance similar to 7.62x39mm and affords a shooter the ability to fire supersonic or subsonic cartridges (suppressed or un-suppressed) without any modifications made to the rifle or pistol.
This quick little guide explains the 300 Blackout cartridge, what parts it requires to function, and which configuration is best for building a well-rounded, reliable, accurate shooter. To preempt the questions answered previously: The 300 BLK cartridge is compatible with all AR-15 parts except the barrel. One can "re-chamber" an existing rifle or pistol simply by swapping the barrel. A pistol-length gas system is recommended. One can also build an AR-15 chambered in 300 BLK from an 80% lower receiver - again, the parts are interchangeable with no modification required to accept the new cartridge. Lastly, 300 BLK is designed to work with existing 5.56/.223 magazines and the traditional M4 feed ramps found in most Ar-15s' upper receivers.
300 Blackout?
What’re ya, some kind of hipster?
;-)
7.62x39 is actually very close to 30-30 Winchester as far as ballistics go with the same bullet. And, if your purchasing your ammo vs reloading it, 7.62x39 is cheaper to shoot than .300 blackout. However, for shooting cheap with an AR type platform, 9mm is the way to go. But, for the 9mm AR, 100 yards is about the maximum practical range and 200 yards takes some practice. And, 9mm will shoot subsonic with 147 grain loads.
Is the 9mm you mention configured the same as pistol 9mm?
Oh, not the comparison of the 300 hiccup to the 762x39 and the 30/30.
With light bullets(125-130 grain), the 300 makes the 762 look plenty powerful and the 30/30 look like a workhorse.
The niche the 300 fits is the suppressed heavy subsonic (190+ bullets) from SBR or pistol configs.
And that fits inside the CQB/covert niche and not much else.
The 300 heavy is akin to a suppressed 45ACP in energy and useful range, but in a much more useful and accurate package.
300 light bullet carbine set ups fall under the useful parameters of just about any thing else.
But, hey, enjoy!
Just made a 300 Ham’r upper, blows my 300Blk away.
Newly manufactured brass is now widely available, loading is not a problem, although converting .223/5.56 brass can be a pleasant task. My rifle has never seen a factory round.
Cool. But so is a 556/223 with the proper bullet, or a 762x39 or a 30/0 or a myriad of other calibers. Plus, the 556 carries that capability to ariund 400 yards easily ( 70 grn TSX or Horn GMX with aplomb....
But hey, real hunters use rounds that are more than adequate. Or they ought to. When a misplaced round wont do the job, a full up rifle round usually does.
That said, I routinely use 223/556 carbine for short range Missouri deer, or even my carry mini glock 40.... It all boils down to engagement parameters and performance envelope.
I also have used my 416 Rigby for the same critters ( can you actually have too much gun? Nope).
It's the same cartridge, but it's configured like an AR-15. Most manufacturers call them an AR-9.
Yes. And still sold at WalMart.
You’re certainly right on the technical specifications and ballistic comparisons of 300 bLK to 7.62, .45 ACP, et al.
Except many shooters do enjoy this round because it provides unique advantages, like the ability to swap from supersonic to subsonic and suppressed with nothing more than a magazine change. Most would agree a cartridge with the ballistic performance of .45 ACP and the stability, accuracy, and increased range of the AR platform far out-performs any other sub-gun or pistol configuration.
It’s also important to remember 300 BLK was developed specifically for US special operations. It doesn’t translate into much practical use in the civilian world, but it’s a wickedly fun (and still potent) cartridge nonetheless.
Thanks.
L
Indeed? A pistol /subsonic set up for heavies can interchange with high(er) velocity supersonic loads?
Are not the pistol length subsonic ports incompatible with high(er) pressure supersonic loads without function issue? Hmmm. Didn’t know that. Confirm?
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