Radical Firearms 10.5″ 458 SOCOM Upper Receiver

For those looking at larger calibers for the AR platform, the 458 SOCOM is among the most powerful chamberings for the MSR. Radical Firearms 10.5″ 458 SOCOM upper receiver will pack a punch in a pistol or SBR.

Radical Firearms 10.5" 458 SOCOM Upper Receiver
Radical Firearms 10.5″ 458 SOCOM Upper Receiver

U.S.A.-(Ammoland.com)- I have always been fascinated by what I like to call “Gucci calibers” and “Gucci guns.” From the .50 caliber Beowulf to the 6.8 SPC – I love the rounds that you can’t go down to your local Walmart and buy off the shelf. Recently I have been focusing on adding these caliber guns in my collection.

Awhile ago Radical Firearms sent me one of their complete 6.5 Grendel upper receiver. I had a great time shooting the Grendel so when Radical Firearms asked me if I wanted to check out their 10.5″ barrel length .458 SOCOM complete upper receiver I only had one answer for them. I had to say “yes.”

Radical Firearms .458 SOCOM Upper Reciever

The Radical Firearms .458 SOCOM upper receiver uses a direct gas impingement system. It uses a very low profile .936″ micro gas block. They connected the micro gas block to the receiver by using a stainless steel pistol length gas tube. The system Radical Firearms put together is an excellent system that more that handles the job at hand.

Radical Firearms chose to make the barrel on the .458 SOCOM out of a durable 4150 Vanadium Steel. It has a 1 in 14″ twist rate. Radical Firearms threaded their barrel with a 5/8×32 TPI thread pattern. The best-looking part of the barreled upper receiver is the fantastic looking muzzle brake.

Panzer Muzzle Brake
Radical Firearms Panzer Muzzle Brake

Radical Firearms calls their new muzzle brake a Panzer Muzzle Brake. It takes its name and looks from the famous German Panzer tank barrels from World War II. When I first saw the brake on the barrel, I automatically was able to figure that Radical Firearms modeled it after the brake on the barrels of the old Panzers tanks. I made this observation before I knew the name of the brake. When I looked up the name, it made a lot of sense.

The Radical Firearms complete upper comes with a 9″ First-Gen Hybrid Rail System (FHR). I like the and feel of the rail system. It does use a Keymod system. This system is the only downside to the rail. I would have liked to have seen Radical Firearms use an M-LOK system since according to military test it outperforms the Keymod system by a significant margin. That small change would take this from being a good rail system to an excellent rail system.

Radical Firearms forged the upper receiver using 7075 aluminum which is the same material as the handguard. It also comes with a forward assist with a shell deflector, uses a single feed ramp in the receiver, and also has a custom ejection port door. On careful inspection, I could not find any issue with the upper receiver. It is well built and sturdy. There weren’t any blemishes that I could find.

Radical Firearms complete upper comes with a 9" First-Gen Hybrid Rail System (FHR
Radical Firearms complete upper comes with a 9″ First-Gen Hybrid Rail System (FHR

Radical Firearms designed bolt carrier group specifically for the .458 SOCOM. The BCG is magnetic particle inspected (MPI) and high pressure tested (HPT). What MPI testing does is check the surface and just below the surface for discontinuities by using a magnetic field on the part. The BCG has a melonite coating and is staked.

The Radical Firearms .458 SOCOM looks like a high-end upper receiver. From the Panzer muzzle brake to the hybrid rail system Radical Firearms went the extra mile to make their product look unique. Their looks rival even some of the more expensive uppers on the market. The Radical Firearms 10.5″ barreled complete upper receiver sales for $669.99 at the time of this writing.

The upper receiver is mounted on an Anderson Manufacturing complete pistol lower receiver. Anderson makes a quality lower receiver at a very affordable price point. I have used their lowers on between 30 and 40 of my AR builds and have been happy with the results.

For magazines, I used a couple of CMMG MKW-15 .458 SOCOM polymer magazines. These magazines are the same size as a 30 round 5.56 magazines, but only hold 10 round of .458 SOCOM. This difference is due to the massive size of the round.

Where the 5.56 round is a 55 grain round, the Freedom Munitions Big Grains .458 SOCOM round weighs in at a stout 300 grains. The cartridge uses a round nose/flat point (RNFP) bullet that travels at 1800 FPS. The Freedom Munitions Big Grain round packs a massive punch. This power is why it is the favorite round of a lot of hog hunters.

Where the 5.56 round is a 55 grain round, the Freedom Munitions Big Grains .458 SOCOM round weighs in at a stout 300 grains.
Where the 5.56 round is a 55 grain round, the Freedom Munitions Big Grains .458 SOCOM round weighs in at a stout 300 grains.

Like most odd calibers, the .458 SOCOM round is on the pricey side of things. The Freedom Munitions Big Grains round price works out to be $1.60 per shot which isn’t too bad of a price for the round. This expense is one of the most significant drawbacks about getting into Gucci calibers. Lucky for me Freedom Munitions provided me with the ammo.

I took the pistol AR equipped with the Radical Firearms .458 SOCOM upper receiver to the range to test it out and blow about $160 worth of ammunition in 30 minutes. The gun and the round function flawlessly. I did not have a single stoppage while on the firing line.

Radical Firearms .458 SOCOM upper receiver
Radical Firearms .458 SOCOM upper receiver

Shooting the .458 SOCOM out of the Radical Firearms upper was a double edge sword. It is a blast to shoot and a real head turner. I had several people come over to me to check out the AR pistol and the Freedom Munitions Big Grains .458 SOCOM round. The common question was, “how much does it kick?”

The answer is “a lot.” This recoil is the downfall of the .458 SOCOM in this configuration. To me, it feels like the recoil from a 20 gauge shotgun. This recoil is a little too much for an AR pistol without a brace that would let the shooter shoulder the firearm like a stock. With a stock or arm brace, the recoil would be easily manageable.

Plans for 458 SOCOM SBR

I am planning on using this upper receiver on a short barrel rifle once my tax stamp comes back from the ATF. I think this is probably the market Radical Firearms is going after. People who spend $200 on a tax stamp will usually want style along with functionality. That is what they get with this upper receiver.

Shooting the Radical Arms pistol equipped with Diamondhead popup back up sites, I was shooting tight groups at 15 yards. The accuracy will improve once the tax stamp for my SBR comes through from the ATF.

It is a well constructed upper receiver that functions well. Radical Firearms offers a 16″ version for the same price as the 10.5″ complete upper receiver. For a hunting firearm that might be the way to go.

About John CrumpJohn Crump

John is a NRA instructor and a constitutional activist. He is the former CEO of Veritas Firearms, LLC and is the co-host of The Patriot News Podcast which can be found at www.blogtalkradio.com/patriotnews. John has written extensively on the patriot movement including 3%’ers, Oath Keepers, and Militias. In addition to the Patriot movement, John has written about firearms, interviewed people of all walks of life, and on the Constitution. John lives in Northern Virginia with his wife and sons and is currently working on a book on the history of the patriot movement and can be followed on Twitter at @crumpyss or at www.crumpy.com.