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AeroPrecision
The Aero Precision M4E1 350 Legend assembled upper receiver brings a modern, billet-style aesthetic to your .350 Legend build without the custom-shop price tag. This 20-inch carbine upper comes fully assembled and ready to pair with your lower, threading you straight into a compact, hard-hitting platform perfect for hunting, home defense, or intermediate-range shooting. The enhanced forging process gives it that premium look while maintaining the durability you expect from a mil-spec upper, and it arrives with the port door and forward assist already installed—one less thing to wrangle on your workbench.
The M4E1 upper is engineered around Aero's Enhanced Series compatibility, so if you're running one of their handguards, you'll get a seamless, professional finish. The updated Picatinny profile plays well with standard optics and rail systems, and the laser-engraved T-marks keep you on target for zero confirmation. The receiver features M4-profile feedramps and .250-diameter takedown pin holes, meaning it'll work with a broad range of compatible lowers and parts ecosystem common to AR-15 pattern rifles.
Because this is an assembled upper, you're looking at a plug-and-play setup once you source a bolt carrier group and charging handle to complete the weapon. It's a smart move for builders who want a solid foundation without paying for a complete rifle, or for folks upgrading an existing lower with a fresh, purpose-built 350 Legend upper.
| Caliber | .350 Legend |
| Barrel Length | 20 inches |
| Configuration | Assembled upper receiver |
| Muzzle Threading | Threaded |
| Color | Black |
| Takedown Pin Holes | .250 diameter |
| Feedramp Profile | M4 |
| Included | Port door, forward assist |
| Not Included | Charging handle, bolt carrier group |
The M4E1 upper is built to standard AR-15 specifications with .250-diameter takedown pin holes, so it'll mate with any compatible AR-pattern lower. Just confirm your lower is chambered appropriately or be ready to swap it if you're moving from a different cartridge.
You'll need a bolt carrier group and charging handle at minimum. The port door and forward assist come installed, so assembly is straightforward once you have those two parts and a compatible lower receiver.
No. The upper arrives with a threaded muzzle end, but any brake, flash hider, or suppressor adapter is sold separately. You can thread your choice of muzzle device depending on your intended use.
The .350 Legend is a compact, straight-wall cartridge great for hunting in jurisdictions that restrict bottleneck rifle rounds, and it shoots flatter than pistol calibers while keeping recoil mild—making this 20-inch upper a tidy option for hunters and shooters who want AR ergonomics without a full .308 or 6.5 Creedmoor footprint.
AeroPrecision
The Aero Precision M4E1 350 Legend assembled upper receiver brings a modern, billet-style aesthetic to your .350 Legend build without the custom-shop price tag. This 20-inch carbine upper comes fully assembled and ready to pair with your lower, threading you straight into a compact, hard-hitting platform perfect for hunting, home defense, or intermediate-range shooting. The enhanced forging process gives it that premium look while maintaining the durability you expect from a mil-spec upper, and it arrives with the port door and forward assist already installed—one less thing to wrangle on your workbench.
The M4E1 upper is engineered around Aero's Enhanced Series compatibility, so if you're running one of their handguards, you'll get a seamless, professional finish. The updated Picatinny profile plays well with standard optics and rail systems, and the laser-engraved T-marks keep you on target for zero confirmation. The receiver features M4-profile feedramps and .250-diameter takedown pin holes, meaning it'll work with a broad range of compatible lowers and parts ecosystem common to AR-15 pattern rifles.
Because this is an assembled upper, you're looking at a plug-and-play setup once you source a bolt carrier group and charging handle to complete the weapon. It's a smart move for builders who want a solid foundation without paying for a complete rifle, or for folks upgrading an existing lower with a fresh, purpose-built 350 Legend upper.
| Caliber | .350 Legend |
| Barrel Length | 20 inches |
| Configuration | Assembled upper receiver |
| Muzzle Threading | Threaded |
| Color | Black |
| Takedown Pin Holes | .250 diameter |
| Feedramp Profile | M4 |
| Included | Port door, forward assist |
| Not Included | Charging handle, bolt carrier group |
The M4E1 upper is built to standard AR-15 specifications with .250-diameter takedown pin holes, so it'll mate with any compatible AR-pattern lower. Just confirm your lower is chambered appropriately or be ready to swap it if you're moving from a different cartridge.
You'll need a bolt carrier group and charging handle at minimum. The port door and forward assist come installed, so assembly is straightforward once you have those two parts and a compatible lower receiver.
No. The upper arrives with a threaded muzzle end, but any brake, flash hider, or suppressor adapter is sold separately. You can thread your choice of muzzle device depending on your intended use.
The .350 Legend is a compact, straight-wall cartridge great for hunting in jurisdictions that restrict bottleneck rifle rounds, and it shoots flatter than pistol calibers while keeping recoil mild—making this 20-inch upper a tidy option for hunters and shooters who want AR ergonomics without a full .308 or 6.5 Creedmoor footprint.
