Tech Tips

What do I need to build my Aero Precision EPC-9?

The foundation of the EPC product line is the EPC-9 receiver. These receivers are machined from custom 7075-T6 aluminum forgings and include all proprietary parts installed from the factory. These proprietary parts include the following: magazine release, last round bolt hold open assembly, and ejector.

Bolt Carrier

The Aero Precision EPC-9 9mm Bolt Carrier Group is machined from 8620 steel and features a nitride finish, fracture-resistant grade 23 titanium pin, and 4140 steel extractor, the EPC bolt assembly is precision machined from the ground up to meet the extreme demands of blowback AR platform firearms.


The barrel is arguably one of the most important components in your build. Aero Precision has a full lineup of 9mm barrels that are compatible with the EPC and other AR9 platforms. These barrels are manufactured with the same quality and attention to detail as our AR15/AR308 you know and love. Each Aero Precision EPC barrel is designed to work in a direct blowback system. This means there is no gas port and no need for a gas block and gas tube!

Buffer Assembly

The EPC buffer kit is optimized for use in the EPC and other AR9 platforms. Featuring a custom 7.7 oz buffer and M5 carbine spring, our EPC buffer kits are designed to meet and exceed the demands traditionally brought on by blowback AR9 platforms. You can purchase the EPC buffer and M5 carbine spring standalone, to use in conjunction with a mil-spec buffer tube of your choice, or as a part of a kit including our enhanced buffer tube.

Lower Parts Kit

Each EPC Lower Parts Kit comes with all the small parts you need to finish your EPC build (detents, springs, and optional fire control group and grip). These kits do not include the proprietary components for your lower receiver, as they are pre-installed from the factory. The components in Aero’s lower parts kit are mil-spec with the exception of the trigger and hammer pins, which are hardened to meet the demands of blowback AR9 builds.

*NOTE: If purchasing a third-party trigger assembly, we advise using a trigger designed specifically to be used in an AR9 platform.

Handguards and Furniture

The EPC-9 upper receiver utilizes mil-spec threads, meaning it is compatible with most handguards that will fit a mil-spec AR15 upper receiver. This includes Aero’s full lineup of ATLAS handguards as well as most third-party AR15 handguards. The EPC-9 lower receiver is compatible with most AR15 pattern grips.

*Note: The trigger guard is integrated into the EPC lower receiver, so grips that feature an integral trigger guard are not compatible.