The Aero Precision M4E1 Upper Receiver is to AR-15’s what Apple is to smartphones.

I’m not going to tell you the Aero Precision M4E1 Upper is the best AR-15 upper receiver ever, but it’s pretty darn close.

With the continuous picatinny rail, the all new Gen 2 handguard, and the revolutionary barrel nut system, this is as close to the “Perfect Upper” that I’ve had hands-on experience with.

Before we get into what makes it very unique, let’s go over some of the basic specs.

The Aero Precision M4E1 Upper is “Made in the U.S.A”.

So What’s Included With The Upper?

Aero Precision M4E1 Upper Receiver.
Enhanced Gen 2 Handguard of either Keymod or M-Lok.
7.5″ 5.56 Pistol Length CMV Barrel.
Low Profile Gas Block and Pistol Length Gas Tube.
Product comes assembled.

The 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 (Anodized only)
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

What’s Different About The Gen 2 Enhanced Handguard?

1pc free float design
Built in anti-rotation tabs
Scalloped rails
Continuous top rail
8″ inside diameter fits most muzzle devices and 1.5″ suppressors
Compatible with low profile gas blocks
Gen 2 Feature – Quick disconnect sling socket at the 3, 6 and 9 o’clock positions
Gen 2 Feature – Additional milling along flats to aid with gripping and add visual appeal
Gen 2 Feature – New profile for the continuous picatinny top rail

Is The Barrel Any Good?

5″ 5.56 Pistol Length Barrel Chamber: 5.56
Length: 7.5″
Twist: 1 in 7
Threading: 1/2″x28
Material: Chrome Moly Vanadium
Finish: QPQ corrosion resistant finish both inside and out
Gas Block: .750
Gas System Length: Pistol
Weight: 17.25oz
M4 Barrel Extension
HP and MPI Tested

The main things that you should take away from these specs are:

The barrel has been High Pressure Tested (HPT) and Magnetic Particle Inspected (MPI). This helps ensure that you won’t be receiving a barrel that is out of spec and can handle the pressure of 1000’s of rounds.

2. The Gen 2 Handguard has three Quick Detach (QD) mounts for your 2-point or 3-point sling system.

3. Scallops along the length of the handguard reduces weight as well as gives you a better gripping surface.

My Favorite thing about this upper is the barrel nut system.

With other upper receivers you must time the barrel nut just right in order to align the gas lines perfectly. But with the M4E1 Upper receiver those days are gone.

You simply insert the barrel, tighten down the barrel nut, and install your gas line and gas block. That’s it! It really couldn’t get any easier.

Final Thoughts

Sometimes when your building an AR-15 pistol it can be a crap shoot. Either the upper and lower don’t mate up correctly or the action doesn’t cycle correctly. But thankfully that’s not the case with the Aero Precision M4E1 Upper.

So Far, I’m really impressed with the Aero Precision M4E1 Upper.

All of the parts went together like a hot knife through butter, and it shoots like a dream.

The finish is smooth, elegant, and the upper and lower receiver fit snuggly without any play.

During testing we put a couple hundred rounds down range and haven’t experienced a single malfunction or hiccup.

You can say that I’m well pleased with this AR-15 pistol build that was provided to us by Aero Precision.

All bias aside, this upper receiver is worth a lot more money than what Aero Precision is asking for it.

Stay tuned and we will review the rest of the Aero Precision parts for you.