How To Build Your Own HK 416 Via Brownells BRN4 Upper

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Brownells is one-stop shopping for most anything that shoots. Amidst sundry accessories, reloading gear, furniture, gunsmith tools, and gun-related widgets literally beyond counting, they also offer some really cool AR15 components. In the past that has included splendid replicas of very early AR15 variants not available anyplace else. They also produce drop-in AR180 uppers for standard AR15 lower receivers. In the Brownells BRN4, we find something that is truly professional grade. 

The House of Mouse

It was May of 2011, and my family and I were enjoying a delightful trip to Disneyworld in Orlando, Florida. Nowadays you have to own a private jet just to get in the gate. Back then, however, normal folk could still manage the cost.

We were thoroughly spent and needed a break. As evening descended, we staked out a convenient spot to take in the Main Street Electrical Parade. The friendly Disney workers set up the ropes that cleared the road for the upcoming parade. There was an omnipresent buzz as thousands of happy vacationers prepared for the show. Then something changed.

Starting at one end of the crowd, something weird propagated through the accumulated mass of people like a contagion. At the time, we didn’t own a cell phone. I look back on those innocent days with fondness. We had no clue what was happening outside the confines of the park. Just as we began to grow alarmed, however, somebody vaulted over the rope and ran the length of the parade route shouting, “We got him! We got him! We just killed bin Laden!”

There in the most magical place on earth, the accumulated throng raised their voices as one to celebrate the fact that, on the other side of the world, a US Navy SEAL had just killed the most evil man in the world. Strangers embraced, and we all basked in our corporate identity as Americans. It was a truly surreal experience. 

Operational Details

On 2 May 2011, two dozen elite Navy SEALs descended upon a fortified compound in Abbottabad, Pakistan, in a pair of highly-modified stealth Blackhawk helicopters under cover of darkness. The objective of the mission, titled Operation Neptune Spear, was to kill or capture Osama bin Laden, the architect of the 9/11 terrorist attacks. The SEALs were on the ground just under 40 minutes.

As is so often the case, things began to go wrong right at the outset. One of the Blackhawks flown by the TF160th Night Stalkers encountered a vortex ring state when descending below the level of the compound’s walls and crashed. However, these were the most highly-trained special operators on Planet Earth. They quickly adapted to the changing situation and continued the mission.

It is generally accepted that a SEAL named Rob O’Neill fired the fatal shots. Coming up on bin Laden’s bedroom on the third floor of the structure, he found the angle and shot the man twice in the forehead with a pair of 77-grain open-tip match rounds out of his HK416 assault rifle. The monster was dead where he dropped.

The Gear

These SEAL Team 6 operators availed themselves of the finest hardware mankind could produce. This meant Mk48 light machineguns, HK MP7 personal defense weapons, and HK416 5.56mm assault rifles. The HK416 was originally developed as a collaborative effort between Heckler and Koch and the US Army’s Delta Force back in the 1990’s.

The HK416 started with the basic chassis of the M4 carbine. HK engineers then adapted the short-stroke, gas piston-driven action of the Armalite AR180 to drive the gun instead of the traditional direct gas impingement system. The piston-driven action was cleaner and cooler than the legacy design and subsequently more reliable. Though a bit heavier than the previous gas gun, the resulting weapon was shockingly rugged. It was also just stupid expensive.

That’s not hyperbole. HK imports a semiauto version of the HK416 today. Where an inexpensive direct gas impingement M4 can be had for $500 or less, the same gun with the piston-driven action and “HK” stamped into the side will set you back five grand. This gun has some serious cred, so a lot of American civilian shooters want one. However, $5,000 isn’t just front pocket change. That’s proper folding money. What’s a brother to do?

Brownells to the Rescue

I assume the patents on the original gun have expired. Regardless, the mad geniuses at Brownells now offer the BRN4. This is a part-for-part copy of the HK416 offered as a drop-in upper receiver assembly. They sell these uppers with 10.4, 14.5, and 16-inch barrels in either medium or heavy contours. The upper is a drop-in fit for any standard AR lower, but it doesn’t come with a handguard. Brownells will naturally sell you one of those as well.

I mounted my 10.4-inch BRN4 upper up on a registered SBR lower receiver fitted with Bravo Company furniture. A SilencerCo Omega 36M sound suppressor and cop-surplus Trijicon ACOG completed the package. Just because I could, I also added a forced reset trigger.

I had access to an original HK416 and stripped the two guns down side-by-side. The parts do indeed appear to be interchangeable. There have been some complaints online about finishing marks and such on the Brownells upper receiver. That was not my experience. My copy is both gorgeous and perfect. It also runs like a rabbit on Red Bull.

Trigger Time

The BRN4 has a slightly different personality when compared to a more conventional M4 gas gun. The overall weight is about a pound heavier, and the center of gravity is a bit farther forward. If hefting both the BRN4 and the original HK416 blindfolded you would not be able to tell the difference between the two weapons. The balance is the same.

The extra mass of the BRN4 as well as the shifted CG both conspire to make this gun exceptionally controllable in rapid fire. Muzzle rise and recoil are not real. The manual of arms is identical to that of any AR or M4 you have ever run.

A direct gas impingement AR is theoretically more accurate than the same rifle driven by a gas piston. This is due to the extra mass of the reciprocating parts. However, while I shoot a lot, my marksmanship is not sufficiently refined to tease out those nuances. My BRN4 shoots just as straight for me as any other top-end premium AR rifle might.

If the objective is simply to throw 5.56mm bullets downrange, there are literally hundreds of different ways to do that safely and well. However, the BRN4 accomplishes that mission with so much more style. After a little time behind the gun, you can see why DEVGRU and Delta are so smitten with theirs.

Nicely accessorized, the BRN4 brings the same rarefied tactical capabilities to the table that the original German version might. The Omega 36M suppressor from SilencerCo excises all of the nasty from this short-barreled room-clearing beast while remaining functionally indestructible. The ACOG has more combat cred than any other tactical glass. The synergistic result is indeed the best close quarters combat weapon mankind can contrive.

Size and Speed

A word on barrel length. The effectiveness of the 5.56mm round is dependent upon velocity. These zippy little cartridges were originally intended to be fired from a 20-inch barrel. As barrels got shorter, velocities dropped and these tiny little .22-caliber bullets lost a great deal of their spunk. That having been said, these DEVGRU guys didn’t just fall off the turnip truck. They know what they’re doing. While we can split hairs about downrange thump in short-barreled 5.56mm rifles, but I don’t see any of the naysayers queuing up to get shot with one. If you’re really burdened by the diminution in velocity, just click 14.5 or 16 inches when you order yours.

Lastly, if you haven’t had the pleasure, a forced reset trigger will seriously change your life. Remaining outside the legal definition of a machinegun per federal law, this thing offers a fabulous full auto analog while ensuring that the trigger cycles with each individual shot fired. I landed mine on special for $120 from MIST Distributors. Installation is a breeze. That’s the best $120 I think I’ve ever spent.

Ruminations

Building up your own HK416 clone at home is still not cheap, particularly when you take into account optics and the can. However, it ain’t five grand, either. Even starting from scratch, you can get into a very nice BRN4 for markedly less than the cost of a high-end sporting rifle like a Steyr AUG, a Tavor X95, or an FN SCAR. Once complete, you get superlative ergonomics, exceptional accuracy, and that amazing unkillable action.

Most of us would not make the cut for a Tier 1 counter-terror unit. Those are some of the most selective fraternities in the world. However, if you have a serviceable credit card and the tiniest bit of mechanical aptitude, you can indeed avail yourself of the same iron used by these consummate professionals. While running mine on the range I can, at least for a brief while, imagine myself out saving the world with the big dogs.

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