Epc-9 9Mm/40 S&W Assembled Upper Receiver W/Lrbho Black

The Aero Precision EPC-9 assembled upper receiver is a complete solution for builders looking to run 9mm or .40 S&W in an AR platform. Built on a one-piece forged design, this upper combines the receiver and handguard mounting surface into a single unit—eliminating complexity and adding rigidity. It ships with the last round bolt hold open (LRBHO) assembly already installed, the barrel nut, and the nut wrench you'll need to get started. Drop in your barrel assembly, torque it down, slide on a compatible handguard, and you're ready to run.

The engineering here is solid: the integrated mounting platform and receiver are machined from the same 7075-T6 aluminum forging, which means no flex between components and no stacked tolerances. Aero cut strategic lightening features into the design without sacrificing strength, and the whole thing needs just eight screws to mount a free-floated rail. The upper features standard AR15 takedown and pivot pin lugs, so it plays well with existing parts kits.

One important detail: the LRBHO mechanism is only compatible with GLOCK-pattern magazines. If that matches your magazine preference, you get the practical advantage of the bolt locking back on the last round—no guessing whether you're dry. The upper is cut for Aero's Enhanced and Quantum handguard lines, giving you modular rail options without hunting for adapters.

This is a thoughtfully engineered platform for anyone building a reliable 9mm or .40 S&W AR. Whether you're setting up a suppressed host, a practical trainer, or a competition gun, the EPC-9 gives you a solid foundation and saves you assembly time out of the box.

Key Features

• One-piece forged 7075-T6 aluminum design combines receiver and handguard mount for superior rigidity
• Last round bolt hold open mechanism pre-installed (GLOCK-pattern magazine compatible)
• Free-floated handguard mounting with minimal hardware—eight screws to a locked-down rail
• Strategic lightening cuts reduce weight without compromising strength
• Standard AR15 takedown and pivot pin lugs for parts compatibility
• Compatible with Aero Precision Enhanced and Quantum handguards
• Includes barrel nut and wrench for immediate assembly
• Laser-engraved T-marks for reference

Specifications

Frequently Asked Questions

What magazines work with the LRBHO on this upper?

The last round bolt hold open mechanism is compatible with GLOCK-pattern magazines only. If you're running a different magazine platform, the LRBHO may not function as intended.

What handguards fit this upper receiver?

The EPC-9 is designed to work with Aero Precision's Enhanced and Quantum handguard lineup. The integrated one-piece mounting surface is optimized for these rails.

Do I need to install the LRBHO assembly myself?

No. The last round bolt hold open assembly comes pre-installed on this upper, so you can move straight to mounting your barrel and handguard.

What comes in the box?

You receive the assembled upper receiver with LRBHO already installed, an enhanced barrel nut, and a barrel nut wrench. You'll need to source the barrel assembly and handguard separately.