AeroPrecision167528091
M4E1 5.56 Assem Upper Govt 14.5'' Bbl Mid-Length Threaded Blk$615.00
Availability: In Stock
Current Stock: Out of stock
The Aero Precision M4E1 5.56 assembled upper receiver with 11.5" carbine barrel is a complete, ready-to-assemble upper built for shooters who prioritize compact handling without sacrificing modularity. This FDE Cerakote finish upper pairs a government-profile barrel with Aero's ATLAS R-ONE M-LOK handguard, giving you a slim, lightweight platform that accepts standard AR-15 furniture and optics. Whether you're building a home-defense carbine, a truck gun, or a suppressed SBR, this upper ships fully assembled—no gunsmithing required—and works with any mil-spec AR-15 lower receiver. Note: this upper does not include a bolt carrier group or charging handle, and the muzzle device is not pinned or welded, so plan accordingly for your build's final configuration.
The 11.5" carbine-length barrel is forged from 4150 CrMoV steel with QPQ corrosion resistance and features a 1/7 twist rate suited to 5.56 NATO across the full spectrum of bullet weights. The carbine gas system feeds through a .0785" gas port into a low-profile gas block, providing reliable cycling while keeping the upper sleek. M4 feed ramp geometry ensures smooth ammunition feeding, and the barrel includes a standard A2 flash hider mounted (unattached) at the muzzle.
The ATLAS R-ONE handguard brings Aero's reputation for precision to your rail game. Its slim profile and 1.3" inside diameter keep weight down and aesthetics clean, while the integrated top picatinny rail and M-LOK slots at 3, 6, and 9 o'clock give you flexibility to mount lights, lasers, or vertical grips. Quick-disconnect sling mounts at multiple positions support aggressive or tactical handling. The upper receiver itself wears the enhanced M4E1 forging with laser-engraved T-marks, refined picatinny geometry that mates seamlessly with Aero's handguards, .250 pin holes, and both port door and forward assist already installed.
Build-friendly and combat-ready, this assembled upper lets you spend your time on accuracy and training, not assembly headaches.
| Caliber | 5.56 NATO |
| Barrel Length | 11.5" |
| Barrel Material | 4150 CrMoV, QPQ finish |
| Twist Rate | 1/7 |
| Gas System | Carbine length |
| Gas Port Diameter | .0785" |
| Gas Block Journal | .750" |
| Handguard | ATLAS R-ONE M-LOK, 10" length |
| Handguard ID | 1.3" |
| Handguard OD | 1.5" |
| Feed Ramps | M4 |
| Takedown Pin Holes | .250" |
| Finish | Cerakote FDE (upper), Anodized Black (internals) |
| Included Components | Assembled upper receiver, ATLAS R-ONE handguard, barrel, gas tube, gas block, port door, forward assist, A2 flash hider |
| Does Not Include | Bolt carrier group, charging handle, pinned/welded muzzle device |
The M4E1 assembled upper is compatible with any mil-spec AR-15 lower receiver. Your lower simply needs to have standard takedown pins to interface with this upper's .250" pin holes.
The upper is fully assembled and installed, but it does not include a bolt carrier group or charging handle. You'll need to source those separately and install them before the rifle can cycle. Additionally, the muzzle brake is not pinned or welded, so if you're building a rifle (16" minimum barrel), you'll need to have the muzzle device permanently attached to meet ATF regulations.
This upper ships with the assembled upper receiver, the 10" ATLAS R-ONE M-LOK handguard, 11.5" carbine barrel, low-profile gas block, carbine-length gas tube, port door, forward assist, and A2 flash hider. Bolt carrier group and charging handle are sold separately.
Yes. The ATLAS R-ONE features a full-length top picatinny rail for any standard picatinny-mount optic or accessory, plus M-LOK slots throughout for lights, foregrips, and tactical gear. It also has quick-disconnect sling mounts at 3, 6, and 9 o'clock positions.
SKU: 167528953 • Weight: 3.52oz
Availability: In Stock
Current Stock: Out of stock
The Aero Precision M4E1 5.56 assembled upper receiver with 11.5" carbine barrel is a complete, ready-to-assemble upper built for shooters who prioritize compact handling without sacrificing modularity. This FDE Cerakote finish upper pairs a government-profile barrel with Aero's ATLAS R-ONE M-LOK handguard, giving you a slim, lightweight platform that accepts standard AR-15 furniture and optics. Whether you're building a home-defense carbine, a truck gun, or a suppressed SBR, this upper ships fully assembled—no gunsmithing required—and works with any mil-spec AR-15 lower receiver. Note: this upper does not include a bolt carrier group or charging handle, and the muzzle device is not pinned or welded, so plan accordingly for your build's final configuration.
The 11.5" carbine-length barrel is forged from 4150 CrMoV steel with QPQ corrosion resistance and features a 1/7 twist rate suited to 5.56 NATO across the full spectrum of bullet weights. The carbine gas system feeds through a .0785" gas port into a low-profile gas block, providing reliable cycling while keeping the upper sleek. M4 feed ramp geometry ensures smooth ammunition feeding, and the barrel includes a standard A2 flash hider mounted (unattached) at the muzzle.
The ATLAS R-ONE handguard brings Aero's reputation for precision to your rail game. Its slim profile and 1.3" inside diameter keep weight down and aesthetics clean, while the integrated top picatinny rail and M-LOK slots at 3, 6, and 9 o'clock give you flexibility to mount lights, lasers, or vertical grips. Quick-disconnect sling mounts at multiple positions support aggressive or tactical handling. The upper receiver itself wears the enhanced M4E1 forging with laser-engraved T-marks, refined picatinny geometry that mates seamlessly with Aero's handguards, .250 pin holes, and both port door and forward assist already installed.
Build-friendly and combat-ready, this assembled upper lets you spend your time on accuracy and training, not assembly headaches.
| Caliber | 5.56 NATO |
| Barrel Length | 11.5" |
| Barrel Material | 4150 CrMoV, QPQ finish |
| Twist Rate | 1/7 |
| Gas System | Carbine length |
| Gas Port Diameter | .0785" |
| Gas Block Journal | .750" |
| Handguard | ATLAS R-ONE M-LOK, 10" length |
| Handguard ID | 1.3" |
| Handguard OD | 1.5" |
| Feed Ramps | M4 |
| Takedown Pin Holes | .250" |
| Finish | Cerakote FDE (upper), Anodized Black (internals) |
| Included Components | Assembled upper receiver, ATLAS R-ONE handguard, barrel, gas tube, gas block, port door, forward assist, A2 flash hider |
| Does Not Include | Bolt carrier group, charging handle, pinned/welded muzzle device |
The M4E1 assembled upper is compatible with any mil-spec AR-15 lower receiver. Your lower simply needs to have standard takedown pins to interface with this upper's .250" pin holes.
The upper is fully assembled and installed, but it does not include a bolt carrier group or charging handle. You'll need to source those separately and install them before the rifle can cycle. Additionally, the muzzle brake is not pinned or welded, so if you're building a rifle (16" minimum barrel), you'll need to have the muzzle device permanently attached to meet ATF regulations.
This upper ships with the assembled upper receiver, the 10" ATLAS R-ONE M-LOK handguard, 11.5" carbine barrel, low-profile gas block, carbine-length gas tube, port door, forward assist, and A2 flash hider. Bolt carrier group and charging handle are sold separately.
Yes. The ATLAS R-ONE features a full-length top picatinny rail for any standard picatinny-mount optic or accessory, plus M-LOK slots throughout for lights, foregrips, and tactical gear. It also has quick-disconnect sling mounts at 3, 6, and 9 o'clock positions.
SKU: 167528953 • Weight: 3.52oz