MPN: APAR700325M52 / APAR700725M52


  • Caliber: 6.5 Grendel
  • Finish: Type III Class 2 Hardcoat Anodized Finish
  • Upper Receiver: Aero Precision M4E1 Threaded Upper - 7075-T6 Aluminum
  • Handguard: 15-Inch ATLAS S-ONE or R-ONE Handguard of choice
  • M4 Feed Ramps: Yes
  • Muzzle Device: A2 Flash Hider
  • Barrel: 18" 1:8 Twist 416R Stainless Steel Barrel (SPR Profile)
  • Muzzle Thread Pattern: 5/8"-24 TPI
  • Gas Block: Aero .750" Low-Profile Gas Block
  • Gas Tube: Rifle-Length Gas Tube
  • Bolt Carrier Group: Not Included
  • Charging Handle: Not Included
  • HP and MPI Tested
  • SPR Profile

*This upper assembly does not come with Bolt Carrier Group and Charging Handle

*ATLAS S-ONE Handguard: Front and rear picatinny rail section. Eliminated center of top rail for weight reduction.

*ATLAS R-ONE Handguard: Full top picatinny rail


  • Weight: ~4 lbs.
  • Length: ~26.4"


  • AR-15 lower receivers


  • 1x Aero Precision 18" 6.5 Grendel M4E1 Complete Upper Assembly


6.5 Grendel is a very capable caliber for long-range shooting. It has a relatively flat shooting trajectory and packs a decent amount of power. If you are looking to build an AR rifle chambered in 6.5 Grendel, Aero Precision has a 6.5 Grendel M4E1 Complete Upper Assembly for you.

High-Quality 18-Inch Barrel

This Upper Assembly comes with a High Pressure Tested and Magnetic Particle Inspected 18-inch long barrel made from 416R Stainless Steel. The barrel has a 5/8"-24 thread pitch and comes equipped with an A2-style flash hider. The gas system consists of a low-profile gas block and a rifle-length gas tube, which works great with the long 18-inch barrel.

Slime Profile M-LOK Handguard

This upper assembly features a slim profile M-LOK handguard. You can choose between the Aero Precision ATLAS S-One or R-One handguard, both of which are made from 6061-T6 aluminum and have M-LOK slots with scalloped rails. The S-One has a small Picatinny rail section on the top for sights, whereas the R-One has a full-length Pic Rail.

The receiver itself is made from 7075-T6 Aluminum and is also HP and MPI tested. It also features M4 feed ramps for improved reliability.

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  • This Item: Aero Precision 18" 6.5 Grendel M4E1 Complete Upper Assembly
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    MSRP: $730.00
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