An Easy Way to Train With 300 Blackout.

by Clay Martin on August 26, 2014

Recently, GunsAmerica has been diving into all things 300 Blackout. Today’s spotlight is on a very special set from Barnes Precision Machine–an AR-15 with uppers in both 5.56 and .300 AAC Blackout. Why two upper receivers? That is the brilliance of the Blackout. 300 AAC, designed from the ground up to work with all existing AR-15 components except the barrel. Magazines, bolt, and all the internal parts are identical. If it was easier to switch barrels in an AR-15, I could use any existing AR I own for 300. In fact, the company that provided the ammo for this test uses cut down 5.56 brass to produce its .300 AAC case. Also by design, you cannot easily chamber a 300 round in a 5.56, or vice versa due to case shoulder dimension. But that still hasn’t answered the question at hand. Why two uppers?


5.56 and 300 AAC compliment each other across a wide range of tactical solutions. I believe Blackout will soon become the weapon of choice for law enforcement–it was practically purpose-built for urban use. Inside of 250 yards, there is not much difference in the trajectory of these two rounds. But the Blackout is packing, on average, twice the bullet weight. Inside of 100 yards (most every law enforcement shooting I have ever heard of is inside this range), you also have the option of subsonic ammo. 300 AAC is available in up to 220 grain subsonic, which is a lot of oomph for such a small package.
One barrel is stainless–the other is black. While simple, the color of the barrel is an easy indicator of caliber.

One barrel is stainless–the other is black. While simple, the color of the barrel is an easy indicator of caliber.

Subsonic, even without a sound suppressor, is surprisingly quiet. You would still want to wear hearing protection, but the sound is significantly less than standard velocity ammo in either caliber. As an urban combat round, Blackout truly shines. The only real down side to Blackout for this application (at the current time) is the price. Blackout averages out around 82 cents per round as opposed to 33 cents for 5.56. And Urban Combat training requires shooting. Lots of it.

That’s the first reason. It is easy to train with 5.56. By simplified math, it takes me 2 cases of 5.56 to pay for my second upper receiver. I specifically ordered my 5.56 and 300 uppers to be identical for this reason. I can train relatively cheaply with my 5.56 gun, and then slap on the Blackout upper and I am ready to go. All of my CQB training has been done with an identical gun, but I am packing a much harder hitting round when its time to ride the breech. This also saves wear and tear on my go to work gun. Upper receiver parts rarely break, but it can happen. At the end of the day, I would much rather go into harms way with a gun having shot 500 rounds instead of 5,000.
With the right set up, the 300 AAC makes an effective hunting gun.

With the right set up, the 300 AAC makes an effective hunting gun.
What if don’t see a lot of CQB action?

The same holds true for hunters. I shoot from the prone when I am accuracy testing a gun, but I have never shot an animal from that position. And very rarely a person. Unfortunately the real world doesn’t look like a golf course. Back in USMC sniper school, the instructors called it perfect world prone, and they were right. Once a gun is zeroed and we have learned how to pull the trigger, practicing the prone position doesn’t do a lot for us.

300 AAC is a better choice than 5.56 for any large animals such as hogs or deer, but I dislike spending close to a dollar per trigger pull practicing shooting positions. Recoil is very similar in these two platforms, so using the 5.56 for training and the 300 for hunting is a very viable option. As a hunting platform, you could also build an upper receiver for different occasions. An 18-20 inch 5.56 for varmint and longer range shooting, a 14.5 inch pinned flash suppressor (or shorter with SBR paperwork) 300 AAC for larger game. Blackout doesn’t depend on velocity so much as bullet weight, and as such is much more viable in a short barreled weapon. 300 AAC is hell on hogs.
One you’re comfortable punching paper, you have to move to more practical training. The low cost of the 5.56 will be a plus.

One you’re comfortable punching paper, you have to move to more practical training. The low cost of the 5.56 will be a plus.
Why not be ready?

From a survivalist standpoint this set up also makes a lot of sense. At a savings of 5 pounds ( for the lower receiver), you gain the ability to use two kinds of ammo. It would also make sense to set up the 5.56 receiver as a DMR style weapon with a scope, using the shorter 300 receiver with a red dot as your urban combat gun. Switch between uses only takes about 30 seconds. If you buy the second upper complete with a bolt (identical to both guns), switching over is even faster, and you are carrying the most needed spare parts in an AR-15.

Let’s go back to the question. Why two uppers instead of two guns? Price. Outside of the barrel and hand guard, what are the two next most expensive parts on a AR? The trigger and the stock. A good stock can set you back $200-300 dollars, and so can a trigger. I always put AR gold triggers into my guns, and next to the barrel the trigger is the biggest component of accuracy. Quality is not cheap though, and this is one place where you should not skimp. I have seen plenty of cheap triggers rattle apart in short order, and its never pretty. For any type of working gun, I want the best stock I can lay hands on, one that will take some abuse. My current favorite is the Magpul UBR, which retails for $265. Those two components together are not cheap, but you only have to buy them once.

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One Response to “An Easy Way to Train With 300 Blackout.”

    February 18, 2015 at 10:43 am #

    Careful else you go the way of England. Honest working people cannot possess a handgun in the U.K. so only criminals are armed. Leads to fealings of insecurity.

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