Diamondback Firearms 300 AAC Blackout Upper

You really do need a .30 cal AR in your life.

So it’s 2018 and the soy boy 5.56 NATO market is over saturating the United States like you would an overpriced hooker’s face in some Far Eastern Asian country. You wake up that morning and realize that just about everyone, including their illegitimate mothers, has a 5.56 AR-15 variant laying around the house. Sometimes you just want to try something different; enter the .300 AAC Blackout, developed by Robert Silvers of Advanced Armament Corporation for the needs of United States special operations groups.

In short, it’s a .30 caliber intermediate round that can be chambered into an AR pattern rifle and is designed to have ballistics similar to its commie scum cousin the 7.62x39mm Soviet.


Why would you want a .30 AR-15 in your Life?

Aside from the freedom to do so, my purpose behind purchasing a .300 Blackout upper for is hunting medium-to-large size game. In several states the .223 Remington is not allowed for hunting. Thankfully, being in the wonderful Republic of Texas, the .300 Blackout is not only allowed, but encouraged.

.300 Blackout has risen in popularity here for taking care of the dreaded feral hog menace, often stopping the little bastards with a single shot. Seeing it as a viable option, having several unfinished lower receivers, along with a surplus of parts available I went to the internet–debit card in hand–to see what I could find. Sifting through a myriad of upper receivers of questionable quality (looking at you Radical Firearms, you know what you’ve done) I managed to find a high quality yet relatively inexpensive upper from DiamondBack.


The Upper

I caught the upper receiver on sale for $234.99 USD, after shipping it came out to a grand total of $254.50. Two weeks later a postal worker who was pouring sweat delivered a  bright white box proudly proclaiming “made in AMERICA” to my doorstep. After unboxing and checking the upper receiver over I was surprised at the quality of the build for such an economical price point. It came with your standard instruction manual and a cool sticker that I put on one of my gun safes.

The 16-inch KeyMod rail was not bent or off-center in any way and has a really natural feel when reaching out to grip it. Personally I am not a fan of the KeyMod system and would prefer a standard Picatinny rail or an M-lok to fit my current accessories. Regardless the full-length handguard was stout, and I was able to grip it firmly without slicing my hands up, unlike previous experiences with KeyMod systems.

I was pleasantly surprised when I dropped the upper onto my Anderson lower. It was an extremely tight fit between the two receivers and required no modifications from shim kits, that often happen in frankengun builds.

On the inside of the gun I did find some metal shavings left over from the manufacturing process, along with what I am guessing are leftover brass shavings from the test firing phase of the quality control process. While this was not a major concern, a moment or two of cleaning remedied the situation–something I would have done anyway with a new firearm.



Shooting Stuff Portion

My lovely outdoor range was a cool 92 degrees, with 80% humidity. Welcome to summertime in Texas.

I was a bit limited on my ammo selection due to not only my wallet but the availability in the area. The two ammo types I had to work with are Magtech 123gr FMJ supersonic and Remington 120gr OTFB. Having more of the Magtech available I choose to use that load to zero at 100 yards.

The optic I was using for this test was the Monstrum Tactical S330P 3×30 Compact Prism Scope, a budget-minded scope that I had mounted on a .22LR rifle. This was not going to be the primary scope for this rifle, but fit the bill for my testing purposes.

The first trigger pull had me hitting the dirt at a hundred yards. Readjusting the sight took a little while as someone decided it would be funny to reverse the directions on the scope. After a few more rounds I had the rifle properly sighted in at 100 yards.

The .300 Blackout to my surprise was not that bad in the recoil department for a .30 cal round. I can best describe it as less than a commie Starbucks sipping AK-47, and more along the lines of a lighter recoiling lever action 30-30. It was easily controllable and the barrel is extremely accurate–more so than the author.


100 yards


50 yards

Both ammo types ran flawlessly through the upper with no malfunctions during the limited testing that was done.  I did notice that the rifle prefers Magtech over Remington in terms of accuracy but both where sufficient at 100 yards.

The only issue I ran into was the Monstrum Tactical scope. After getting sighted in the elevation knob fell off. What did I expect from a $90 scope…



Overall I like it. It fits the needs I built the gun for short range, hunting, and target engagement. The .30 cal round does not kick as bad as its commie cousin, making follow up shots a breeze. The upper receiver was better than I expected, being highly accurate, reliable and reasonably priced. Of course I must say that this was a short test of under 100 rounds total, so for long term the jury is still out, however I am quite impressed. So much so that I am already looking at a Diamondback 5.56mm carbine at my local gun shop.

So if you’re looking for a high-quality upper receiver that won’t bust the bank, take a look at Diamondback firearms for your next build.



Franken-gun .300 AAC Build

Bolt Carrier Group

Palmetto State Armory 5.56 Premium Bolt Carrier Group

Charging Handle

Lee Unlimited Standard Charging Handle

Lower Franken Gun Receiver

Anderson Manufacturing Am-15

CMMG  Lower Parts Kit

Magpul MOE grip OD green

UTG Model 4/AR15 A2 Fixed Stock Assembly


Magpul P-mag 10 round


Monstrum Tactical S330P 3×30 Compact Prism Scope


Birchwood Casey Shoot-N-C  12” round target


Upper Receiver

Diamondback 16″ 300 black out


Pierce Tomas

Pierce Tomas

Your typical Texan gun enthusiasts and wannabe writer who spent several years working as domestic security guard for private and government installations.

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