Suppressor Optimized 300 Blackout Complete Upper

Brownells unveiled the BRN-180SH complete upper—the newest addition to the popular BRN-180 line—announcing it at the IWA Outdoor Classics show in Nuremberg, Germany.


at Brownells
Prices accurate at time of writing


  • Attachment Type: M-LOK
  • Cartridge: 300 AAC Blackout
  • Barrel Contour: Lightweight
  • Make Model Fit: Brownells.  BRN-180. AR-15 Universal
  • Color: Black
  • Gas System Length: NA
  • Barrel Length: 10.00
  • Hand: Right
  • Receiver Style: Complete
  • Finish: Anodized
  • Twist: 1-8
  • Material: Aluminum
  • Muzzle Threads: 5/8"x24

Chambered in 300 Blackout, the BRN-180SH has a 10.5" barrel with 5/8"-24 muzzle threads, and a gas system with three settings—unsuppressed, suppressed, and off.

With the gas system turned completely off, the upper is converted into "single shot" mode, virtually eliminating sound produced by gases escaping through the ejection port or by the bolt carrier group cycling.

When fired with a suppressor attached and the gas system turned off, the BRN-180SH in single-shot is even quieter than a BRN-180S.

The BRN-180SH has an adjustable charging handle that can be turned down to help change the upper into a straight-pull action. This makes it easier to shoot quickly after the first shot when the gun is set to run as quietly as possible.

BRN-180SH has an adjustable charging handle

With a simple twist of the gas adjustment and a turn of the charging handle, the upper can be quickly changed back to shooting without a suppressor.

Like the rest of the BRN-180 line of uppers, the BRN-180SH fits onto any standard AR-15 or BRN-180 lower, and requires no buffer tube assembly. It readily operates with a folding stock or no stock at all.

Product Description From Brownells

With the BRN-180S 300 Blackout being frequently used in conjunction with suppressors, Brownells sought out new features that make the platform quieter and better to use with a suppressor.

Still mounting to any standard AR-15 spec lower receiver, the new BRN-180SH Suppressor Optimized Upper Receiver notably includes a gas shutoff setting. This is not uncommon on piston-driven firearms, it has rarely been utilized as a true "single shot" setting.

Combined with the adjustable charging handle, which can be pointed downwards like a bolt action, the BRN-180SH can be configured into an extremely quiet, fast-charging single shot. Simply adjust the gas system off, then pull the charging handle back and release it to cycle. The single shot function eliminates ejection port escaping gasses, which can increase noise at the shooter’s ear and in general.

If the user wishes to shoot semi-auto, the gas system can simply be set to the suppressed or unsuppressed setting, adjust the charging handle upwards, and run the upper normally. The charging handle can be left downwards but may interfere with the shooter’s firing grip in semi-auto.

Suppressor Optimized 300 Blackout Complete Upper

Other benefits of the BRN-180 remain, and on this new variant, an improved 5/8-24 muzzle thread adapter ensures precise alignment of suppressors with the bore.

The main reason users select the BRN-180, the entirely contained reciprocating mass is retained, so you can use lower receivers with a rear Picatinny rail or folding stock/brace, and fire the upper while folded.

Access to the gas system is straightforward, simply remove the bottom screw and pull the handguard forward off the upper. The AR-180 inspired operating system allows for simple removal from the rear for easy cleaning. The upper ships with a classic A2 flash hider, which caps the 10.5" nitride barrel with a 1-8 twist.

RELATED – Find The Best Barrel Length For 300 Blackout

About Brownells

Serious About Firearms Since 1939, Brownells has been the world’s leading source for guns, gun parts and accessories, ammunition, gunsmithing tools, and survival gear.

With a large selection of both common and hard-to-find items, and an extensive collection of videos, articles, and gun schematics, Brownells is the expert for everything shooting-related.

Committed to maintaining our great traditions, Brownells has more, does more, and knows more—and guarantees it all, forever.

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