8.6 Blackout is the newest big-bore sensation for AR-10s, combining .338-caliber authority with sub- and supersonic flexibility—think of it as 300 BLK’s heavyweight cousin. Because parts support is still ramping up, Arm or Ally stocks hard-to-find essentials in one place. Start with Faxon Firearms and Q LLC 1:3 twist barrels (yes, 1:3) in 8", 12", and 16" lengths that stabilize 300-grain subsonics for whisper-quiet suppressed use while still launching 210-grain supersonics with impressive energy. Our Toolcraft 8.6-spec black-nitride BCGs feature modified ejectors to handle the rebated rim, and we offer dedicated gas tubes, adjustable blocks, and super-heavy buffer setups to keep dwell time perfect. Upper receivers arrive pre-assembled with enlarged ejection ports, and we bundle them with lightweight carbon-fiber or skeletonized aluminum handguards to offset the thicker barrel profile. Because factory ammo is still scarce, we stock Gorilla, Blackwater, and SIG 8.6 Blackout loads when available, alongside resized brass, Hornady .338 bullets, and the fast-burning powders Q recommends for safe handloads. Whether you’re building a short-barreled hog hammer or experimenting with sub-MOA, sub-sonic precision, this category provides the niche components you’d otherwise struggle to source. Bookmark it—inventory moves fast and restock dates on 8.6 parts can be unpredictable.