Sons of Liberty Gun Works M4-76 5.56 NATO AR-15 Rifle - 13.9" - Primary Arms Exclusive

SKU: M4-76-13.9PAE
MPN: M4-76-13.9PAE
3 Reviews

In Stock

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When you need an entry-level AR-15 built with all the features for a reliable, do-it-all carbine, then you need the M4-76 from Sons of Liberty Gun Works. Made exclusively for Primary Arms, the M4-76 5.56 NATO AR-15 rifle has features that enhance performance, like a 13.9" government profile barrel, six groove 1/7 twist rate ideal for 62 grain 5.56 NATO surplus ammo, and a pinned and welded Dead Air KeyMo muzzle brake. Its mid-length gas system combined with appropriately sized gas ports and an A5 buffer system minimizes recoil and ensures reliable function under various conditions.

  • 5.56 NATO / .223
  • 13.9" 4150 Chrome Moly Vanadium Steel Barrel
  • Pinned and welded Dead Air KeyMo muzzle brake
  • HPT and MPI
  • QPQ Nitride Finish
  • 1/7 Twist Rate
  • Mid-Length Gas System
  • 4140 Steel .750" Gas Block
  • M76 M-LOK Free Float Handguard
  • 1/2x28 Threaded
  • 7075-T6 Aluminum Cerra Forged Receivers
  • Rebellious Stripes Lower Receiver
  • Type III Class 2 Hardcoat Anodized Black
  • Radian Raptor Charging Handle
  • Liberty Fighting Nickel Boron Trigger
  • Magpul MOE Grip
  • B5 Systems Stock
  • Intermediate A5 Buffer System
  • T-Marked Upper
  • Dry Film Lube Bolt Carrier Channel

An M76 free float handguard with M-LOK slots provides plenty of space for attaching optics and accessories for the perfect set-up. The M76 handguard attaches with a wedge lock barrel nut, known for being one of the most durable and reliable on the market. It also features 45° M-LOK slots located near the front to provide more room for mounting light and accessory options.

The upper receiver is constructed from 7075-T6 aluminum Cerro Forgings with a black type III class 2 hardcoat anodized finish for durability. It boasts a forward assist, dust cover assembly, and a SOLGW BCG and Radian Raptor ambidextrous charging handle. Inside the receiver, dry film lube is applied to decrease friction on the bolt carrier group and ensure smooth functioning. The lower receiver has upgraded furniture with a B5 Systems carbine stock and Magpul MOE pistol grip for improved ergonomics and control over standard Mil-Spec equipment. A Rebellious Stripes engraving on the lower receiver is excellent for added aesthetics.
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Barrel CoatingSalt Bath Nitride
Barrel ContourGovernment
Barrel Length13.9
Barrel LiningSalt Bath Nitride
Barrel Material41V50 Chrome Moly Vanadium Steel
BrandSons of Liberty Gun Works
Caliber Gauge5.56 NATO
Gas System LengthMid-Length
Gas System TypeDirect Impingement
Magazine Capacity30
Muzzle DeviceDead Air KeyMo Muzzle Brake
Thread Pattern1/2 X 28
Twist Rate1:7
California Prop 65 warning

 WARNING: This product can expose you to chemicals, which are known to the State of California to cause Cancer and Reproductive Harm. For more information go to

Ratings & Reviews

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SOLGW 13.9"


Limited edition rifle nearly identical to the12.7" M4-76, I own one of those too. This one came with a Surefire War Comp and a very thin shim on the 13.7" barrel to make 16" vs the SOLGW NOX and 12.7" barrel.
<br> Rifle shoots very softly with the A5 buffer system. It's gassed properly which is refreshing in a mostly overgassed industry. Runs like a scalded dog when shooting 5.56*. Rifle length is great for maneuvering around obstacles and transitioning in and out of vehicles. Absolutely love the trigger in this thing. Very clean break and nice reset.
<br> *If you plan to shoot .223 and or steel case plinking ammo plan on getting an A5H0 buffer with this one as the weak .223 didn't cycle the Rifle. I tried a variety of .223 and none of the brands would work. The buffer weight change and a peer check by the SOLGW customer service got me back straight.
<br> You cannot go wrong with a SOLGW product.

They’re out of stock everywhere for a reason


SOLGW is absolutely top notch in every sense of the word. If you’re familiar with them, I’m sure you’re already following them on IG. There’s details on this rifle you just don’t realize you’re getting until you’ve shot more “budget friendly” options. Down to even taking the slop out of the safety selector. I’ve put a few hundred rounds downrange so far with zero issues. If you’re torn between this and the 13.7, they’re identical other than muzzle device. This has the Surefire Warcomp which is slightly shorter than SOLGW Nox, hence the .2” difference in barrel length to get it to the 16”. You will not be disappointed with the rifle or the SOLGW family.



This is the best all around AR on the market.