AeroPrecision144603131
Aero Precision M4E1T Complete - Upper 10" Barrel 300Blk$590.98
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Availability: In Stock
Current Stock: Out of stock
The Aero Precision M4E1T Complete Upper with 8\" barrel in .300 Blackout is a factory-assembled short-barreled upper receiver built for shooters who want a compact, modular platform without having to source and fit components individually. This complete upper pairs Aero's M4E1 threaded receiver with their new ATLAS R-ONE handguard and a purpose-built .300 Blackout barrel, making it an efficient choice for SBR builds, suppressed shooting, or tight-quarters tactical setups where barrel length and overall profile matter.
The M4E1 upper receiver features enhanced forging that blends a billet aesthetic with practical functionality: full M4 feedramps, .250 takedown pin holes, laser-engraved T-marks, and integrated port door and forward assist. The receiver accepts mil-spec AR15 components and is ready to accept your choice of bolt carrier group and charging handle (sold separately). The ATLAS R-ONE handguard is engineered for weight consciousness and minimal profile while offering genuine real estate for attachments—a full-length top Picatinny rail, QD sling sockets at 3, 6, and 9 o'clock, and compatibility with low-profile gas blocks. Inside diameter is 1.3", outside 1.5", keeping the rig compact without sacrificing modularity.
The 8\" barrel is 4150 chrome-moly vanadium with QPQ corrosion-resistant finish inside and out. It runs a pistol-length gas system and ships with a .750 low-profile gas block and A2 flash hider (muzzle device is not pinned or welded, giving you flexibility for permanent installation or suppressor mounting). The barrel is HP and MPI tested and comes complete with M4 feed ramp extension. At 18 ounces, it keeps weight down where it counts.
This is a complete upper receiver assembly only—you will need a bolt carrier group and charging handle to run it. It does not include a lower receiver or fire control group. Perfect for builders who know their platform and want a no-nonsense, battle-tested foundation for a dedicated .300 Blackout short rifle or pistol build.
| Upper Receiver Type | M4E1 Threaded |
| Barrel Caliber | .300 Blackout |
| Barrel Length | 8\" |
| Barrel Material | 4150 Chrome-Moly Vanadium |
| Barrel Finish | QPQ (corrosion-resistant, inside and out) |
| Twist Rate | 1:7 |
| Barrel Weight | 18 oz |
| Gas Port Diameter | .109\" |
| Gas System Length | Pistol |
| Muzzle Thread | 5/8x24 |
| Gas Block | .750 Low-Profile |
| Muzzle Device | A2 Flash Hider (unattached) |
| Handguard | ATLAS R-ONE |
| Handguard ID | 1.3\" |
| Handguard OD | 1.5\" |
| Top Rail | Full-length Picatinny |
| QD Sockets | 3, 6, and 9 o'clock |
| Receiver Compatibility | Mil-spec AR15 |
| Feedramps | M4 |
| Takedown Pin Holes | .250\" |
| Assembly Status | Factory assembled, upper only |
This is an upper receiver assembly only. You will need a bolt carrier group, charging handle, and lower receiver to build a complete rifle or pistol. The upper comes assembled and ready to accept these components.
Yes. The M4E1 threaded upper receiver and ATLAS R-ONE handguard are compatible with mil-spec AR15 upper and lower combinations, so you can mate it to a standard 80% lower or any mil-spec lower you already own.
The barrel is threaded 5/8x24, which is compatible with .300 Blackout suppressors. The A2 flash hider is not pinned or welded to the barrel, so you can remove it and attach a suppressor or other muzzle device of your choice. If you intend to permanently attach a suppressor for a registered SBR, you'll need to pin or weld it per local and federal law.
The R-ONE offers a full-length top Picatinny rail for optics, lights, or other rail-mounted gear. It also includes QD sling sockets at 3, 6, and 9 o'clock positions for flexible sling mounting. The handguard is compatible with low-profile gas blocks and maintains a slim 1.5\" outside diameter, keeping your build compact and lightweight.
SKU: 144602541 • Width: 3.9in • Height: 4.15in • Depth: 23.45in • Weight: 3.06oz
Availability: In Stock
Current Stock: Out of stock
The Aero Precision M4E1T Complete Upper with 8\" barrel in .300 Blackout is a factory-assembled short-barreled upper receiver built for shooters who want a compact, modular platform without having to source and fit components individually. This complete upper pairs Aero's M4E1 threaded receiver with their new ATLAS R-ONE handguard and a purpose-built .300 Blackout barrel, making it an efficient choice for SBR builds, suppressed shooting, or tight-quarters tactical setups where barrel length and overall profile matter.
The M4E1 upper receiver features enhanced forging that blends a billet aesthetic with practical functionality: full M4 feedramps, .250 takedown pin holes, laser-engraved T-marks, and integrated port door and forward assist. The receiver accepts mil-spec AR15 components and is ready to accept your choice of bolt carrier group and charging handle (sold separately). The ATLAS R-ONE handguard is engineered for weight consciousness and minimal profile while offering genuine real estate for attachments—a full-length top Picatinny rail, QD sling sockets at 3, 6, and 9 o'clock, and compatibility with low-profile gas blocks. Inside diameter is 1.3", outside 1.5", keeping the rig compact without sacrificing modularity.
The 8\" barrel is 4150 chrome-moly vanadium with QPQ corrosion-resistant finish inside and out. It runs a pistol-length gas system and ships with a .750 low-profile gas block and A2 flash hider (muzzle device is not pinned or welded, giving you flexibility for permanent installation or suppressor mounting). The barrel is HP and MPI tested and comes complete with M4 feed ramp extension. At 18 ounces, it keeps weight down where it counts.
This is a complete upper receiver assembly only—you will need a bolt carrier group and charging handle to run it. It does not include a lower receiver or fire control group. Perfect for builders who know their platform and want a no-nonsense, battle-tested foundation for a dedicated .300 Blackout short rifle or pistol build.
| Upper Receiver Type | M4E1 Threaded |
| Barrel Caliber | .300 Blackout |
| Barrel Length | 8\" |
| Barrel Material | 4150 Chrome-Moly Vanadium |
| Barrel Finish | QPQ (corrosion-resistant, inside and out) |
| Twist Rate | 1:7 |
| Barrel Weight | 18 oz |
| Gas Port Diameter | .109\" |
| Gas System Length | Pistol |
| Muzzle Thread | 5/8x24 |
| Gas Block | .750 Low-Profile |
| Muzzle Device | A2 Flash Hider (unattached) |
| Handguard | ATLAS R-ONE |
| Handguard ID | 1.3\" |
| Handguard OD | 1.5\" |
| Top Rail | Full-length Picatinny |
| QD Sockets | 3, 6, and 9 o'clock |
| Receiver Compatibility | Mil-spec AR15 |
| Feedramps | M4 |
| Takedown Pin Holes | .250\" |
| Assembly Status | Factory assembled, upper only |
This is an upper receiver assembly only. You will need a bolt carrier group, charging handle, and lower receiver to build a complete rifle or pistol. The upper comes assembled and ready to accept these components.
Yes. The M4E1 threaded upper receiver and ATLAS R-ONE handguard are compatible with mil-spec AR15 upper and lower combinations, so you can mate it to a standard 80% lower or any mil-spec lower you already own.
The barrel is threaded 5/8x24, which is compatible with .300 Blackout suppressors. The A2 flash hider is not pinned or welded to the barrel, so you can remove it and attach a suppressor or other muzzle device of your choice. If you intend to permanently attach a suppressor for a registered SBR, you'll need to pin or weld it per local and federal law.
The R-ONE offers a full-length top Picatinny rail for optics, lights, or other rail-mounted gear. It also includes QD sling sockets at 3, 6, and 9 o'clock positions for flexible sling mounting. The handguard is compatible with low-profile gas blocks and maintains a slim 1.5\" outside diameter, keeping your build compact and lightweight.
SKU: 144602541 • Width: 3.9in • Height: 4.15in • Depth: 23.45in • Weight: 3.06oz