Aero Precision M4E1 Threaded 16" 5.56 M4 Barreled AR-15 Upper Receiver - 15" M-LOK ATLAS S-ONE Handguard

Manufactured by Aero Precision
SKU: APAR700305M6
MPN: APAR700305M6
Manufactured by Aero Precision
8 Reviews

Out of Stock

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The Aero Precision M4E1 Threaded AR-15 Barreled Upper Receiver is perfect for shooters who are looking for a little more out of their build. The unique receiver forging blends seamlessly into the lightweight ATLAS S-ONE free float M-LOK handguard. The billet look comes without the weight and cost. The barrel nut with taper lock mount allows for an incredibly rigid free floating rail, meaning your sights and lasers will be deflected less than traditional options will be when shooting from the prone or supported.

Note: Barreled Upper Assembly does not include bolt carrier group or charging handle.

  • One piece forged upper receiver
  • Lightweight 15" ATLAS S-ONE free float M-LOK rail
  • Blended flat top receiver rail
  • 16" M4 contour 41V50 chromoly vanadium steel barrel with durable nitride finish is high pressure tested and magnetic particle inspected
  • 1:7 twist stabilizes even the heaviest 5.56 NATO bullets
  • Matching M4 feed ramps for receiver and barrel
  • Billet aesthetics without the billet cost or weight
  • Fully compatible with standard AR-15 bolt carrier groups and charging handles (available separately)
  • Effective A2 flash hider

The ATLAS S-ONE free float M-LOK handguard features an interrupted top picatinny rail, allowing for enhanced ergonomics and reduced weight in an area that very few shooters actually utilize for accessories. Instead the top of the handguard is equipped with indexing grooves for a sure grip when driving the muzzle. The M-LOK slots at the 3, 6, and 9 o'clock positions are ready to accept your favorite lights, lasers, and grips, while the integrated QD sling swivel sockets ensure you don't need to waste accessory space for a dedicated mount. The ATLAS uses a functional and aesthetically pleasing taper-lock  system for rock solid mounting.

Under the handguard is a 16" 41V50 chrome moly vanadium steel barrel. Chambered for the incredibly common 5.56 NATO, the barrel features 1:7 twist rifling that will stabilize the full range of bullets available up to 77-grain. The balanced M4 contour features a reliable carbine length gas system fed by a low profile gas block. The durable inky black salt bath nitride finish is exceptionally corrosion resistant and does not negatively impact accuracy the way old school hard chrome linings can. Threaded 1/2x28, the barrel is ready to accept your favorite AR-15 muzzle brakes, compensators, or flash hiders, and even ships with the highly effective A2 style bird cage flash hider.

The Aero Precision M4E1 Threaded AR-15 barreled upper receiver perfectly blends precision machining, quality components, and eye-catching ergonomics perfect for nearly any build, simply add your favorite sights, bolt carrier group, and charging handle.
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Barrel CoatingSalt Bath Nitride
Barrel ContourM4
Barrel Length16
Barrel LiningSalt Bath Nitride
Barrel Material41V50 Chrome Moly Vanadium Steel
BrandAero Precision
Caliber Gauge5.56 NATO
FinishHardcoat Anodized
Gas System LengthCarbine
Gas System TypeDirect Impingement
Handguard15 in Aero Precision ATLAS S-ONE M-LOK Rail
Muzzle DeviceA2 Flash Hider
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

8 reviews

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A+ item from an A+ shop!

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Purchased this item for a fantastic price from Primary Arms during a sale they were having. Fit my Aero Precision M4E1 lower like a dream. As snug as you can get. Loaded it up with a Toolcraft BCG and a cheap charging handle, and it ran like an absolute dream. I extremely like the slim profile of the Atlas S-One handgaurd. It can heat up after a few rounds, but its not unbearable. High quality item for a bargain price. Primary Arms is a pleasure to order from as well!

Great stuff.

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Very nice product, good fit and finish on spikes, psa, and aero lowers. Tools were also included and had a nice padded box. Shoots great and would recommend for next build if you are looking for a lightweight slim hand guard and I would buy again.

Really great quality.

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Excellent fit with my spikes lower. One of the best fits I've ever felt in an AR. No wiggle or rattle. The quality feels every bit as good as any BCM upper I've held and it's extremely light. Don't even want to say "for the price" because I think it compares handily to stuff twice the price.

Great people to do business with !


Great upper for the money worked great on a Anderson lower rock solid PA service is the best ! Had some problems with another upper they took care of it in less then 1 hour thank you primary arms ! Great people to do business

Buy one if you can!

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Love this upper. Have it paired to a PSA lower and it shoots great. Threw a bcg and CH in and was ready to go to work. Nice fit and couldn’t be happier. The thing I love is the weight, it’s super light.

Wonderful Upper!


Definitely will buy again. Smooth upper rails, and the weight is light and balanced.

I screwed up !


I should have bought 5 of these when they were on sale !!! The one I purchased shoots like a laser , I put a vg6 on it and it's loud but so much fun to shoot . When available put one in your safe ,thank me later !

Damn fine upper

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A good replacement for my oddly formed M&P sports 2! While switching BCG's on my Sports 2, it was obvious that it wasn't fitting the parts I needed. Got this as a replacement and boy was I not disappointed! Everything about this screams upper range while still in a well priced budget.

The lack of charging handle and bcg aside...I had the parts laying around and I assume you are as well. If not, our fine friends here can help ya out with a mil spec one!