M4E1 Enhanced 10.5" 5.56 Barrel Quantum Handguard Complete Upper Receiver

Aero Precision 10.5" 5.56 Quantum Handguard Complete Uppers

M4E1 Enhanced 10.5" 5.56 Barrel Quantum Handguard Complete Upper Receiver Product Sku: APPG640002P2

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This Complete Upper includes our Quantum Handguard! Key features include the addition of built in anti-rotation tabs, removable 4-slot picatinny rail section for front sight and a 7 mounting surface for accessories.


  • M4E1 Enhanced Assembled Upper Receiver
  • Quantum Handguard of choice
  • 10.5" 5.56 CMV Barrel
  • Low Profile Gas Block and Carbine Length Gas Tube
  • Product comes assembled
  • This complete upper does not include BCG or Charging Handle. These products may be selected as add-ons under the Finish Your Build tab
  • The muzzle brake that comes with this complete upper receiver is NOT pinned nor welded to this barrel. Per the National Firearms Act, the muzzle brake MUST be pinned and welded to achieve the necessary 16" as defined by the ATF for a rifle build.

M4E1 Upper Features:

  • Forged from 7075 T6 aluminum
  • Precision machined to M4E1 specs
  • M4 feedramps
  • Matte black hard coat anodized Mil 8625 Type 3 Class 2
  • Laser engraved T-marks
  • Comes assembled, with port door and forward assist installed
  • Accepts standard AR15/M16 components
  • Handguard mounting platform is forged into the receiver
  • Works with Aero Precision handguards but also fits most BAR-system handguards
  • Barrel nut and wrench are included

Quantum Handguard Features:

  • 1pc free float design
  • Removable 4-slot picatinny rail section for front sight
  • Built in anti-rotation tabs
  • 7 mounting surfaces for KeyMod accessories
  • 1.78" inside diameter fits most muzzle devices and 1.5" suppressors
  • Compatible with low profile gas blocks

10.5" 5.56 Barrel Features:

  • 5.56 Nato 10.5" Barrel, 1/7 twist, 4150 CrMoV, QPQ, gas port drilled
  • .750 gas block journal
  • Carbine length gas system, .0785 gas port
  • M4 Feed Ramp Extension
  • HP and MPI tested
  • Standard A2 flash hider
Made In America? Yes
Platform AR15
Series M4E1
Caliber 5.56 NATO
Barrel Length 10.5"
Weight(s) KeyMod: 43.04 oz / M-LOK: 43.04 oz
Other No

Customer Reviews

4 Item(s)

Perfect upper for my pistol build Review by Stephen
When building my pistol I decided on this upper and waited for a few range trips to write this review. That being said, this is a strong upper for the money. As other reviewers have noted, the Magpul MBUS front sight will not depress fully, I solved this by lightly shaving down the plastic wings of the MBUS front sight until it would reliably press down to release and still offer a small amount of space between the rail. When attaching a sling to this rail I've found it to be rock solid and have yet to noticeably change my zero even when carrying the rifle by the sling extended periods of time so any deflection has been minimal.

One thing I love about this rail is how well it fits my hand, it's a good size for both a traditional underhand grip and a C-clamp grip. I have no doubt this would pair well with an angled foregrip without becoming too thick to comfortably grip. (Posted on 12/31/2017)
Excellent Review by Chris
Took this out to the range to zero, test accuracy and conduct a few drills. I was highly impressed. Shot around 300 rounds with zero failures. Zeroed and did accuracy testing with 55gr Silver Bear, shot my drills with 62gr Federal XM855. Average groups at 100m were 3.6"; best group was 1.8"; worst group was 6". I was running a Holosun 403B for the optic. This is a great upper for the price. The quality is outstanding. Just to put it into perspective, the 16" upper I have with a 10x scope was shooting an average of 2.9 moa...only a 0.7 moa difference. This would be a solid upper for a fighting gun. (Posted on 6/27/2017)
10.5" Pistol Build - VERY impressed.. Review by Carl
I finally got my Aero Precision 10.5" pistol build finished and took it to the range today to test... VERY impressed with the workmanship of Aero's products (upper and lower). My only complaint and a word of warning to any potential buyers for the upper... the front pic rail sits very close the handguard and as such you can't use a set of Magpul Mbus sights as the unlocking mechanism doesn't work. You will have to fit a set of Magpul Pro sights... I had hoped to included a picture of the final build... (Posted on 5/12/2017)
Great upper Review by Craig
I put this upper on an Aero lower I built as a pistol. Using a red dot with a 3x magnifier I was getting about 2" groups at 100 yards and chest size hits at 200 yards from the bench. With a normal rifle scope I may have better groups. At about 100 rounds it has worked flawlessly. I have the M-LOK version and Magpul covers were tight and the plastic Magpul front sight does not work because the lever hits the forend and cannot pop up. The rail does see fat compared to the ALG on another AR build. I also do not see the point of the forward assist and wish they would stop putting them on uppers. (Posted on 5/7/2017)

4 Item(s)

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