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BRN-180S™ GEN2 300 BLACKOUT 10" COMPLETE UPPER RECEIVER ASSEMBLY Reviews & Ratings

BRN-180® Upper Receiver Group Gen2 – Reliable Piston System Made Even More Versatile

Designed in conjunction with PWS & FM Products, the Brownells BRN-180® Complete Upper Receiver is inspired by the Armalite® AR-180 of the 1960s. Developed as a successor to the original AR-15, the AR-180 was a civilianized version of the AR-18, itself an upgrade on the M16 platform. The BRN-180® incorporates many of the AR-18/AR-180 improvements - including its robust and reliable gas piston operating system. (Yes, the originators of the AR-15 / M16 eventually embraced a piston!) The BRN-180® Gen2 Upper Receiver Group improves upon the original BRN-180 with two main upgrades. First, all BRN-180® Upper Receivers now ship with an Adjustable Gas System, previously only found on the BRN-180S®. The operating mechanism, the short stroke gas piston concept remains the same, but the user can select between two settings, depending on their conditions and ammunition, to ensure smooth and consistent function. No more spare gas piston cup to worry about. In addition to the new Adjustable Gas System, the Handguard is now retaining with a single locking screw. This large screw provides ample locking force and ensures a more consistent handguard lockup than the previous mechanism. During extended firing, and the barrel heating up, this new locking system ensures the handguard retains alignment and rigidity with the upper receiver. Also, with this new takedown mechanism, the handguard can be removed to access the gas system without removing the internal components. Like the original, the BRN-180® bolt carrier rides smoothly on a PAIR of guide rods. The carrier is buffered at the rear by a built-in polymer buffer with a molded-in steel plate that captures the guide rods. The Nitride bolt replicates the original AR-180 bolt design, right down to its use of a standard AR-15 extractor. Wait - we know what you're dying to ask. Yes, the BRN-180® upper receiver is fully compatible with any standard, mil-spec AR-15 lower receiver.

The 10” barrel is machined from extra-strong 4150 carbon steel, with a hard Nitride finish that really resists surface wear. This BRN-180S® is chambered in 300 Blackout for extra flexibility in ammo choice - with 1-8" rifling. Standard 5/8-24 tpi muzzle threads let you swap on a modern AR-15 muzzle device should you be bitten by the customizing bug.

Ultra-reliable AR-180 piston operating system
Compatible with current mil-spec AR-15 lowers
Machined 7075 T6 aluminum receiver & handguard - hardcoat anodized finish
10" nitride barrel
300 Blackout Chambering
Button rifled bore; 1-8" twist
5/8-24 threaded muzzle
Molded polymer ejection port cover
Total weight: 4 lbs

All NFA rules apply.

User removal of the trunnion, barrel and trunnion screws is not recommended. Removal of the trunnion screws will void our Lifetime Guarantee.

All BRN-180 Upper Receiver Assemblies are test fired before final packaging. Upper may display signs of firing, such as or slight fouling inside.

See all of our AR15s and AR15 parts here.

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2 Stars

Reviews Summary

The BRN-180S GEN2 in .300 Blackout receives mixed reviews, with many praising its reliability, smooth shooting, and compact design. However, some users expressed concerns about the adjustable gas block, non-standard muzzle threads, and various functional issues related to cleaning and parts compatibility, leading to a divided opinion on its overall quality.

What Reviewers Are Saying

Product Performance

70%

Customers highlight the BRN-180S's smooth shooting and reliability, with many noting its accuracy, especially with subsonic rounds. However, some users reported inconsistent groupings and issues with cycling when using suppressors, raising questions about its performance under various conditions.

Build Quality and Design

60%

Reviewers appreciate the overall design and build quality, with mentions of its balance and lightweight nature. Issues such as the polymer parts (dust cover and guide rod cap) and non-standard muzzle threads generated a mix of satisfaction and concern over durability and functionality.

Usability and Functionality

65%

Many users noted the ease of use and operation of the BRN-180S, but also pointed out significant usability issues like the problems faced during disassembly due to the op-rod and adjustable gas block. These design quirks affected the overall shooting and maintenance experience.

Customer Support and Resolution

40%

Customer experiences with Brownells’ support have been mixed, with some receiving helpful responses while others faced frustrations regarding repairs and returned units not functioning as expected. The quality control around specific models was also called into question due to multiple defects reported.

Customization and Accessories

55%

Reviewers expressed a desire for more customization options, particularly associated with muzzle devices and the adjustable gas block. Additionally, some noted challenges regarding compatibility with aftermarket parts and accessories, indicating room for improvement in this area.

Customer Photos & Videos

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Fun gun

Very fun to shoot this thing suppressed. I haven't put enough rounds through it to claim good reliability but it hasn't had any issues so far. Its also my only 300 blackout upper. Its fun, im keeping it.

Would you recommend this? Yes, I would recommend to a friend

by PETER KNAPP on March 22, 2025

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Very impressed

Excellent rifle. Super balances and smooth shooting! I have a psa JAKL and there is no comparison. This Gen2 is much more reliable than the jakl and has much better balance.

Would you recommend this? Yes, I would recommend to a friend

by BRIAN SHIELDS on February 01, 2025

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Was this review helpful? 5

300BO 10inch Upper

Purchased this Nov 2024 in a Black Friday sale. This is a fantastic little upper. Very compact, very accurate and quiet. I managed close to 1" groups at 100yds with S&B 200gr subs with a AAC suppressor and 6X scope. I have other BRN180 uppers in 223/5.56 which are similar performance. Precision Weapons Systems designed and manufactured these in conjunction with Brownells. Top notch!

Would you recommend this? Yes, I would recommend to a friend

by Dee on January 30, 2025

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Was this review helpful? 0

Almost Perfect

This upper is the centerpiece of a 300 Blk suppressed pistol. Piston action and adjustable gas are ideal. Minor quibbles; would prefer 9" barrel & left side charging.

by GREGORY NEWKIRK on August 31, 2024

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BRN-180 GEN 2 300 BLK UPPER

Overall I'm happy with this purchase. There were a few scratches on the upper when I opened the box, but I'm going to paint it, so it's a non-issue. I wish I could just buy the complete gun, to make the process easier.

by DONALD JACKSON on February 19, 2024

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Was this review helpful? 4

Brn-180S

I thought I'd submitted tis review earlier but it seems I never actually sent it. Here goes again: I've had my BRN-180S in 300 Blackout for a couple years now. I picked an Aero Precision lower for it to ride on and after replacing the trigger group with a Wilson Combat 3-Gun trigger unit, found it to be a comfortable shooter though I replaced the 3-prong flash hider with a different compensator (had a devil of a time getting the factory one off!!). I love this set-up. It shoots well; I've fired light 125 g fmj out of it along with 150g Winchester extreme point, all the way to the plastic tipped 220g, all without a hiccup. I only have two only nits (sit enough to affect my rating). #1 is the cranked charging handle, First off, I don't like it sitting that high where I can see it moving with each shot. The other is that when shooting, it often ricochets a spent cartridge back into my face. I fixed easily by getting an after-market straight charging handle. The other nit is that doe to the manner of constriction of the bolt unit, springs and rear cap, there is nothing to hold that rear cap against the upper when you open the weapon up. If you are just not paying close attention when opening the rifle, that entire reap plate and springs will shoot out like a rocket and perhaps bash you in the face. I have submitted a recommended simple fix that will retain the rear plate when you open the weapon. All in all, even considering the two nits I mentioned, I love everything about this firearm. It's a toss-up between the BRN-180 and my Daniel Defense PDW as my go in an emergency.

Brn-160S

I'm a retired Military officer with just shy of 30 years of service. I've had my 180S 10" bbl in 300 BLK for about 2 years now and still love it. Initially I bought an Aero Precision lower with Maxim collapsible brace for it but am considering buying a Brn lower and build it myself. It has always shot well and it extremely reliable. I normally load it with Winchester 150g plastic tipped rounds but have gone as heavy as 206 G Hornady without any issues. I did find two nits with it, not enough to lower my rating. I found that the cranked charging handle occasionally deflected fired cases into my face. I also found that, when opening the receiver, unlike a standard upper, you need to make ALWAYS make sure a thumb or finger is always on the back of the receiver, or it will launch the rear cup/springs assembly into the atmosphere (or your face). I fixed the empty cases ricochetting into the face with an after-marker straight charging handle and sent a recommended simple fix to Brownells re. a simple rotating rear restraining tab for the back of the receiver to restrain the rear end.

Brn 180 300aaf

Have not shot it yet but I play with it everyday. Go to the range in the rain that is how excited I am about the purchase !!

by Brian Szramowski on December 21, 2023

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Was this review helpful? 0

BRN-180S 300 BLK

I wanted to build a gun so that I could shoot with the stock folded and the BRN 180s was the perfect match. Built with high end parts on lower to give it a nice fit. Shoots smooth and love how its recoil feels versus a rear buffer tube ar15. When I shoot it with my dead air sandman S it puts a smile on my face ! No problem so far with it cycling any of the ammo I used so far, suppressed or unsuppressed

Sweetness

It works. Little heavy upfront but that actually helps manage the already manageable recoil of 300. Plan on suppressing. Might have gas port drilled out a bit if its undergassed on suppressor setting like others have experienced. Pretty solid deal for a descendant of the ar-18. It gets hot. I have a rail wrap on the way. Should help with the heat