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Brownells BRN-180

Brownells Resurrects the AR-180 With the BRN-180

The AR-18 was developed by Armalite not long after the AR-15 in the early 1960s. The goal was to create a 5.56mm rifle that wouldn’t infringe on the licensing agreement Armalite made with Colt for the AR-15, and a key component of this was the modified direct-impingement system. The AR-18 was designed with a short stroke piston system for this reason. The AR-18 and its semi-auto sibling, the AR-180, were never a commercial success. No military ever adopted it, and less than 21,000 units and variants were produced, with production ceasing in 1985. While a casual observer might think it ignominiously sank without trace, the operating system of the AR-18 would go on to heavily influence the designs of the SA-80, Howa Type 89, Bushmaster M17, HK G36, and the Bushmaster/Remington ACR.

New(ish) to New
The new Armalite under Mark Westrom launched the AR-180B in 2001. It was something between retro and modern with some strange compromises that made it less desirable to both collectors and modern shooters at the same time. It maintained the profile of the original AR-180, including the original optics mounting system, while also eliminating the classic dog leg-style charging handle and including a new polymer lower that used regular AR fire control and standard AR mags versus the original proprietary units. Classic collectors weren’t very interested because it wasn’t true to form, and modern shooters thought it lacked features they wanted like a Picatinny top rail. After about six years, the AR-180B was discontinued.


Old (bottom) versus new (top) contrasts stamped sheetmetal with CNC’d aluminum.

When Brownells announced the BRN-180 upper at SHOT Show 2019, we were eager to get our grubbies on it. It was clear that Brownells respected the classic design, but also included updates for the modern shooter. Rather than producing a dedicated AR-180 clone, the company wisely chose to produce an upper that’d fit on any of the many millions of existing AR-15 lowers in circulation.

The action had to be shortened slightly to work with standard AR lowers, but it doesn’t appear anything was lost when doing so. The fit between the BRN-180 upper and any of the lowers we tried was superior to the fit of the original AR-180s, which are, to put it nicely, rather sloppy. The upper incorporates a slim free-float M-LOK rail with a top Picatinny rail. The rail comes off to access the piston system for cleaning. The barrel is nitride coated and chambered in .223 Wylde with a 1:8 twist, giving the BRN-180 the ability to accurately and safely shoot all modern loadings. Classic features of the right-side dog-leg charging handle and three-prong flash hider are maintained for a unique aesthetic.

That svelte M-LOK rail looks hot. After a couple of mags, it is.

A benefit to the BRN-180’s operating system is that it doesn’t require the use of a buffer and spring. Twin recoil springs and guide rods are fully enclosed inside the upper receiver, giving the user the option to install a side folding stock without any hassle. It also means the BRN-180 can’t ever have a problem like carrier-tilt, as with other piston uppers.

On the Range
What better way to test this new throwback than by a ton of competitions? By using it at these events it’d encounter a wider range of environmental and shooting circumstances than it would at a normal range.

The first testing configuration consisted of an AGP Arms forged lower with one of their side folding stock assemblies. This stock folds flush to the right side of the receiver and isn’t blocked from doing so by the charging handle. The downside with folding to the right is the BRN-180 can’t be fired with the AGP stock folded (if you care about that). The AGP is a nice, lightweight option if you’re only going for reducing the overall length. Everything else on this lower was Mil-spec, including the fire control to establish a baseline for reliability. I installed a Vortex Crossfire red dot and zeroed it at 50 yards with Wolf Gold 55-grain ammo. Later, we made some changes to a more Gucci competition system with a KE Arms billet lower, Griffin Armament M4SD comp, and SLT-2 match trigger.

Look at the guts of any piston gun adopted by a major nation in the past three decades, and you’ll see a BCG that looks almost identical to this one.

There were a lot of lessons learned over the course of several months as well as many configurations tested. The recoil impulse is different from a standard AR-15 that takes some getting used to. Lacking the traditional buffer system, you can feel the bolt moving back and forth in the upper more causing more sight picture disruption than a tuned AR-15. The BRN-180 is plenty accurate enough to easily engage practical-sized steel targets out to 500 yards.

The handguard is very slim, and the area close to the piston heats up quickly; this was addressed by the SHTF+ heat shield wrap. Whether you use M-LOK rail covers, a vertical grip, or the SHTF+ Wrap, you’re going to want to have something to protect your hands on the forend.

Left-handed shooters may notice casings hitting their right shoulder and arm — not a big deal if you have long sleeves but watch out with T-shirts.

BRN-180 carrier and recoil spring are a bit shorter than its predecessor, but otherwise peas in a pod.

The M4SD Flash Comp completely changed the recoil dynamic. The BRN-180 just sits on target with it installed. There’s very little sight picture disruption, making it easy to hammer close paper and distant steel alike. In short: The upgraded BRN-180 build was now a rifle as capable as any of our tricked-out ARs.

We did witness a malfunction with the BRN-180, but not our own. A fellow competitor had a short-stroke stovepipe, immediately followed by a complicated stoppage involving a nose-first jam with the second ejecting from the magazine and lodging itself behind the bolt. It was a Greek orgy.

With almost a year’s worth of testing in a competition environment, we reckon we’ve given the BRN-180 a fair shake. And we like it.

We tried replicating this malfunction and couldn’t. We first believed it was caused by keeping the dustcover closed, and a mere week later Brownells contacted us and all early adopters that a new dustcover had been made to address this issue. And that appears to be the case.

I didn’t see the BRN-180 shooting any less accurately than equivalent 16-inch DI guns with the same ammo. With Magtech 62-grain ammunition the BRN-180 grouped ¼ inch at 50 yards. We ran into one issue with a 40-round PMag with a +6 extension that resulted in a failure-to-feed. Extra tension from the high-cap extended mag was slowing the bolt down for the first several rounds, until spring pressure lightened up.

Like the FN SCAR-16S, using the magazine as a monopod can cause issues with some magazines. Dimensional differences between PMAGs, Lancers, and USGIs allowed the polymer magazines to make contact with the bolt lugs and slow the bolt enough to malfunction when rested on the deck. There were no problems like this with metal magazines.

Loose Rounds
After 2,400 rounds of testing, the only three malfunctions witnessed are described in this article. That’s pretty exceptional, especially for a brand-new-but-based-on-old design. For the AR collector/hobbyist looking for something different to diversify their collection, the BRN-180 upper is a solid choice.

BRN-180 / 180S Upper
Barrel Length: 16 inches / 10.5 inches
Twist Rate: 1:8
Operation: short-stroke gas piston
MSRP: $800 / $830

BRN-180 / 180M Lowers
MSRP: $130 / $150

Basic Configuration
AGP Forged with Side Folder
MSRP: $1,050

Advanced Configuration
KE Arms Flared Magwell with SLT Trigger and Sig Side Folder
MSRP: $1,885 (optics not included)

We Plead the 2nd
3 Color Desert
MSRP: $250

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  • I Have the Gen 2
    I really like it. Only 1000 rounds through it so far, Haven't had a sing problem.

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