Uploaded November 2025 | Updated September 2026, 1 week ago

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In this video, Caleb from Brownells walks you through a complete 6mm ARC AR-15 upper receiver build. From parts selection to torque specs and setup techniques, this guide is ideal for anyone looking to build or learn more about this precision rifle cartridge. We go over every step, from the lower receiver components to installing the muzzle brake, scope, and bipod. Perfect for new builders and experienced enthusiasts alike.

Chapters:
00:00 - Introduction & Purpose of Build
01:11 - Sons of Liberty Lower Receiver Overview
02:45 - Upper Receiver Components
04:05 - Barrel Installation
07:15 - Dust Cover & Forward Assist
09:58 - Barrel Nut Torqueing Process
12:46 - Installing the Gas Block
14:22 - Handguard Installation
17:27 - Handguard Locking Screws
20:07 - Muzzle Brake & Shim Kit
21:35 - Arca Rail & Bipod Setup
24:34 - Scope Mount & Optic Setup
28:32 - Scope Leveling & Torque
32:00 - Final Assembly: Bolt Carrier Group & Charging Handle
36:34 - Bipod Positioning & Sling Mount
38:06 - Ammo Preview & Wrap-Up