Brownells BRN-180 Gen 2 Sport DIY Build: How To and Testing

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The ArmaLite AR-180 and AR-18, a semi-automatic sporter and selective-fire assault rifle variation of Eugene Stoner and ArmaLite’s later production rifles. Designed in 1963 by Sullivan, Stoner, Dorchester and Miller, the AR-18 was designed as a “cost effective” combat rifle, being cheaper to produce than the Colt M16. Largely produced from steel stampings, the AR-18/180 made for a quality and somewhat unique rifle, considering that it utilized a gas piston, over the AR-15’s gas impingement system. While never officially adopted by any nation’s military, it did see use by the Irish Republican Army (aka IRA) with success against the British, and was the rifle featured in the Irish song “My Little ArmaLite.”

Michelle used components from Brownells to assemble this 5.56x45mm BRN-180 rifle.

Outside of the short use by the IRA, both the 18 and commercial 180 practically fell into obscurity except when the new ArmaLite company (formally Eagle Arms) released the polymer receiver AR-180B for a short time during the domestic assault weapons ban (which lasted for 10 years; 1994–2004). A little over 10 years ago, there were two aluminum lower receiver models manufactured, by the retro AR company NoDak Spud, as replacement options for the plastic AR-180B lower. These were popular with AR-180 aficionados. As a platform however, the AR-18/180 influenced several other rifles, including the popular HK G36. The unique little ArmaLite had practically been lost to time, outside of rifle enthusiasts and collectors. Thanks to Brownells and Primary Weapons Systems the AR-180 not only made a return, but also entered the 21st Century with modularity and styling to match. Enter, the Brownells BRN-180 rifle. Unlike its aging brethren, the Brownells BRN-180 is largely produced from forged aluminum, over the original’s steel stampings. Featuring a free-floated lightweight one turn in seven inches twist barrel, the BRN-180 is quite the lightweight “handy-rifle.” Minor changes from the Generation 1 to Generation 2 made the ‘little ArmaLite’ somewhat more user friendly and in my opinion, a more solid choice for a defensive carbine.

brownells-brn-180-rifle-review-03 — With the stock folded, the already compact and slim design of the BRN-180 becomes even smaller.

While the 180 did lose its quick(ish) detach fore-end and rail system for a threaded screw attachment system, I find this system more rugged and robust. The entire design is very sleek in comparison to the AR-15. No longer is a receiver extension and external buffer system necessary. It is a completely different operating system than the traditional ArmaLite Rifle. Utilizing an adjustable, long-stroke gas-piston system of operation, the compact bolt carrier rides on two guide rods, accompanied by two recoil springs. This twin recoil system balances out the operation of the firearm, making for extremely smooth operation.

Unlike its predecessor, the BRN-180 transfers several components over from the typical AR pattern rifle, including lower parts and the ability to utilize AR pattern, small frame receivers. Luckily, Brownells took it a step further, also releasing two corresponding lower receivers. The BRN-180M lower features modern AR-15-type styling that goes hand in hand with the modern design ques of the modern 180 upper. The other lower offering, designated just BRN-180, however, is styled similar to that of the original 180 lower receiver with the slanted mag well. I like that Brownells is offering the ability to build a complete, yet customizable rifle and pistol platform with their 180s. Being a customizable platform to suit almost everyone’s desires, Firearms News Editor-in-Chief Vincent L. DeNiro built his BRN-180 along the lines of: “What would the AR-18 look like today if it became the service rifle for the U.S. military in the 1960s?” Keeping as true to the original profile as possible, his modernized version included parts from Magpul, Midwest Industries, SIG Sauer, AR180S.com, Jard, MDT, and Manticore Arms. You can read his review in an upcoming issue.

Initial Impressions

brownells-brn-180-rifle-review-04 — The Midwest Industries aluminum and steel constructed folding stock matches nicely to the BRN-180’s finish. While the rubber stopper does help protect the finish of the 180 upper, the folding stock still scuffs the anodizing. Robust, well made, nicely finished, the Midwest Industries folding stock fits well and works great. Note how the handguard not only locks into position with the upper receiver lug, but also both guide rods lock into the handguard as well. Rock solid and robust design.

Having spoken a couple of times with friend and fellow ArmaLite fan Caleb Savant of Brownells on the BRN-180, I was pleased to learn they typically use a mix of CMMG and Sons of Liberty Gun Works components in their lower parts kits. I have always been a fan of CMMG products, and their lower parts kits have long been a “go-to” of mine, due to their consistency, quality and repetition. Another great company, is Sons of Liberty Gun Works. I like that they use KNS 17-4 stainless detents and 17-7 springs, with their springs typically always being from SpringCo/Tactical Springs. I can always count on receiving AISI-8620 investment cast and properly heat-treated lower components (1095 disconnect). The same, ‘boring consistency’ is what I want each and every time. When the upper receiver arrived however, I was supplied with a Geissele/ALG lower parts kit. This contained the ALG “enhanced mil-spec” trigger group, along with all the other standard pins, detents, springs, and components. The Geissele/ALG components contained all Schmid Tool (Geissele marked of course) lower parts, investment cast, along with great looking springs and detents.

brownells-brn-180-rifle-review-05 — Handguard removal is as simple as removing a 5/32 hex head screw. With a couple taps, it comes right off revealing the lightweight barrel and piston system.

When assembling the lower receiver, I noted several things that impressed me. One of which is the threaded bolt release housing. This is typically found on premium billet receiver sets. It was a nice addition to this receiver, and I also like the addition of the rear tensioning screw. Overall, the receivers were nicely finished and uniformly anodized, with a great upper to lower match. The ALG trigger was just, nothing to write home about and was quite “mil-spec.” Breaking at six pounds, it wasn’t that it was a “bad” trigger, it just left a lot to be desired. So, I swapped it for a Airborne Arms Geronimo single-stage trigger. With this the rifle began to feel more ‘in tune’ with what it should be. Being sleek, lightweight, fast handling, the 180 deserves a better than mil-spec trigger. The A2 grip from Luth AR was quickly swapped as well and a spare B5 used in its place. The B5 simply fits my hand better. Using the side-folding, fixed extruded stock from Midwest Industries, the rifle came together quite nicely. The stock has great styling, which lend to the aesthetics of the carbine. While well-built, it does add nearly a pound to the rifle. This comes from its 6061 aluminum and 4140 steel construction. However, the allocation of the weight balances the rifle out quite nicely. While the Midwest Industries stock will work on other firearms, it’s like they designed it for the BRN-180. It offers the optimal cheek weld for lower co-witness optics, iron sights and flows well with the rifle overall.

BRN-180 Pros

brownells-brn-180-rifle-review-06 — Smaller, lighter,and simpler, the BRN-180 operating system is a cleaner alternative to its gas impingement AR-15 and AR-10 brethren. The bolts themselves look quite similar, with locking lugs, ejector and extractor all located in the same place. Note the similarities between the AR-15 and BRN-180. Gas piston adjustments are as simple as “U” for unsuppressed and “S” for suppressed. Two positions simplify things, while still allowing the user to adjust for the situation. The piston block is quite lightweight and low profile, adding to the theme of “compact and lightweight.” Note the simple piston adjustment located on the front of the piston and block assembly.

While I like an adjustable gas system, sometimes firearms can have “too much adjustment.” An example of this is the FN FAL. The BRN-180 has two settings, one for suppressed and one for non-suppressed. This is optimal for defensive use in my opinion, as for defense, simplicity is key. Brownells and PWS really did their homework here and based their adjustments off of an overall reliability aspect, over a “tuning” or recoil reduction aspect. I also like that they are clearly and plainly marked, with clear and audible clicks into position. There simply is no mistaking which position the gas system is in. The free-float rail systems are ones which I like. Using a full-length top rail and MLOK positions at the 3, 6 and 9 o’clock positions allow the user to outfit the carbine with any form of accessory. The rail attachment for the Generation 2 is a singular hex head screw, located on the bottom of the upper. It interfaces with the upper receiver, allowing for quick detachment and access to the gas system, a simple screw removal and light couple of taps removes the rail. On the top of the rail system, there is a witness hole for the gas system adjustment.

brownells-brn-180-rifle-review-07 — The BRN-180 twin guide rods and twin recoil springs. This, coupled with the lighter carrier and piston system offers noted lower felt recoil than an AR Carbine.

Unlike its gas impingement siblings, the BRN-180 uses a substantially longer gas system. From a person coming heavily from direct impingement guns of this style, I was a bit taken aback at the location of the gas block journal. Fortunately, this was all calculated, making for an incredibly reliable and mild recoiling rifle. Using 55-grain and 62-grain 5.56mm NATO ball, recoil was subtle, slow, flat and pleasant. It felt nothing like an impingement AR and had a recoil impulse more like that of a 5.45mm AK-74. Even coupled with its light weight, recoil was easily managed, and accurate, fast follow-up shots were no problem. Unlike the abrupt jolt given by AR carbines, it is more like a slow and gentle shove. I attribute a lot of this to the mass of the carrier, the gas system length and the long-stroke gas piston system. I have fired a bit over 600 rounds through the BRN-180 of various loads, including Russian Tula. In terms of reliability, it ran flawless. Due to the rifle being a long-stroke gas piston system, cleanup was simple. I couldn’t find much “gunk” in the receiver, bolt or carrier and I believe what deposits that were found were simply from excess oil attracting foreign materials.

BRN-180 Accuracy

Overall, accuracy is good in comparison to its peers and excellent when comparing to an original ArmaLite AR-180. With 55-grain M193 5.56mm NATO FMJ, the BRN-180 was easily able to outperform the original ArmaLite by as much as one inch at 100 yards. While my Costa Mesa produced ArmaLite AR-180 shot well and would offer what would be considered “combat effective” accuracy, it is easily overshadowed by the modern Brownells 180. During my brief ownership of the old ArmaLite, I was never able to achieve better than 3 inches at 100 yards, using M193 5.56mm. With M193, the BRN-180 easily shot 2–2.5-inch groups at 100 yards and comparable groups with M855.

brownells-brn-180-rifle-review-08 — Overall, I was very pleased with how accurate the BRN-180 is. The BRN-180 shot very well and rivals other defensive or combat rifles in terms of accuracy. With the light profile barrel, I was happy with the 1- to 2-MOA results overall. For bulk, M855 Armscor 5.56mm, a 1.8-inch, five-shot group is quite acceptable Accuracy. While defensive and Match obviously shoots more consistent groups, I was pleased with this level of accuracy for bulk FMJ. M193, 55-grain 5.56mm FMJ shot consistently better groups than the M855. While minimal, the difference was there. Overall, very pleased with how accurate the BRN-180 is.

This is the second test rifle this year that favored 69-grain Black Hills Sierra MatchKing ammunition over all other tested loads. Accuracy across the board was good using premium ammunition, achieving from 1.5 to two-inch groups at 100 yards with PMC, PPU and Hornady 55-grain soft point. The shining star in the defensive ammunition category though had to be Wilson Combat/Lehigh Defense’s 55-grain Controlled Chaos. This produced respectable 1.25-inch groups at 100 yards. I only achieved sub-MOA groups once and that was with 69-grain Sierra MatchKing handloads, producing a .89-inch five-shot group. Black Hills’s 69-grain MatchKings produced solid and consistent MOA results, while IMI Razorcore and Hornady Match hollow point shot between 1.0 to 1.25-inch groups. Overall, I am pleased with the accuracy potential and accuracy offered by the BRN-180. It performs consistently and produces great groups, especially for such a light barrel profile.

While overall a solid carbine, I dislike how open the upper receiver is and can be. Unlike the AR-15, this is a much more open design, and this leaves the rifle vulnerable to foreign debris, dirt and mud. The charging handle on the Sport is both a blessing and a curse. Unlike the standard handle, which angles up and away from the user, this one is simply a large knob protruding from the carrier. Unfortunately, it takes up a lot of real-estate on the upper. Fortunately, charging handles are interchangeable between the standard and Sport. Heat can become a problem with the BRN-180. Due to the barrel weight, the barrel will heat up quickly under long strings of consistent fire. Groups remained centered, but once heated up they do begin to open between .5 and 1.25 inches. I also noted that, due to the slim nature of the handguard, it seemed to trap heat after prolonged fire, making the fore-end quite warm, but not uncomfortable to the touch. Overall, Brownells did a great job breathing new life back into the ArmaLite AR-180. I like how adaptive the 180 is and while it is not a typical AR pattern rifle, it will accept several components of the AR-15. I like its compact nature, light weight, reliability, recoil impulse and how well it shoots. A solid performer, it would make a great preparedness rifle for any freedom-loving individual. Nice job Brownells!