Brownell's BRN-PROTO 5.56 NATO - 20" Barrel - 25+1 - Black/Brown

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Replica of the Original AR-15 Prototype – As Back To Basics as You Can Get!

Step into the Wayback Machine and go back to the beginning of the AR-15 with our BRN-Proto® – a faithful replica of the Eugene Stoner’s very first AR-15 prototype. If you’re an AR-15 aficionado or collector, the BRN-Proto® is a rifle you should not be without! Based on AR-15 Serial Number One, the Brownells BRN-Proto® sports a wealth of unique, historically accurate features you will not see on later AR-15 / M16 models.

First, the BRN-Proto® has the distinctive trigger-like charging handle on top of the receiver, under the carry handle, just like the early AR-10 models (remember, the AR-15 was developed second.). It has the uncluttered “slick-side” upper receiver of the early rifles and stock, handguard, and pistol grip of brown reinforced polymer that replicates the look – but not the weaknesses – of the original fiberglass furniture. If the round cross-section handguard looks oversized, that’s because it is. Just as the original was a “borrowed” AR-10 ‘guard, it’s actually lifted from our BRN-10® .308 rifles!

The matte gray, anodized receiver – correct color for early rifles – is fitted with a skinny A1-profile barrel capped off with the early three-prong “duckbill” flash suppressor, just like the originals. The BRN-Proto’s front sight base mirrors that of the Number 1 prototype, with a lower profile than we’re used to seeing. The windage-adjustable A1-type rear sight drum is nestled right inside the carry handle.

Each BRN-Proto® comes with one 25-round steel bodied magazine, a distinctive replica of the original that Brownells has designed and manufactured specifically for this rifle. You will not find this early magazine available from any other AR-15 manufacturer.


  • Chambered for modern 5.56x45mm NATO (.223 Remington compatible) ammunition
  • Robust forged/machined 7075 T6 aluminum receivers
  • 20″ barrel with 1-12″ rifling for compatibility with modern ammo
  • Rifle-length gas tube
  • Chrome-plated bolt / carrier group machined from 9310 carbon steel
  • Comes with one 25-rd magazine

A critical addition to the Brownells Retro™ line, the BRN-Proto® AR-15 gives you the looks and “functionality” of the original without the drawbacks. It is constructed of the latest materials using the latest manufacturing techniques, so you have an robust rifle that’s ready to put a LOT of rounds down range. Internal dimensions conform to modern “mil-spec” standards, so the BRN-Proto® is compatible with off-the-shelf upgrade and replacement parts. It’s chambered for modern 5.56 NATO ammo, with a slow-ish 1-12″ rifling twist that’s faster than the original 1-14″ for better compatibility with the 55-grain bullets you find on M193 type ammo (modern AR-15s are usually faster still at 1-7″ or 1-8″).

Get your BRN-Proto® today and enjoy the thrill of owning and shooting a replica of the very first model of America’s favorite rifle.

SKU: 050806113299 Categories: , Tag:


Additional Information
TypeRifle:  Semi-Auto
Caliber5.56 NATO
Receiver7075 T6 Aluminum
HandguardBrown Polymer
SightsFixed A2
Barrel Length20″
Overall Length40″
Weight7.5 lbs
MagazinesOne 25-Round Magazine
Product UPC050806113299

Additional Information Content

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