The LWRCI ICMKII A5 .300 Blackout 10? SBR Upper in Patriot Brown is a rugged, high-end AR-pattern upper receiver built to handle the versatile .300 AAC Blackout cartridge with a short-stroke gas piston system derived from LWRCI’s Individual Carbine program for enhanced reliability and ease of maintenance under heavy use. It features a 10.5? cold-hammer-forged heavy barrel with a 1:7? twist rate and 5/8?-24 TPI threaded muzzle, paired with a user-configurable adjustable two-position gas block allowing tuning for suppressed or unsuppressed shooting. Finished in Patriot Brown Cerakote for corrosion resistance and tactical style, the upper includes an LWRCI proprietary modular rail, LWRCI Skirmish backup iron sights, and an ambidextrous charging handle, making it ideal for building a short-barrel rifle (SBR) that blends durability, performance, and custom styling. LWRC International LWRCI ICMKII A5 .300 Blackout 10" Bbl Patriot Brown SBR Upper ICMKIIU3PBC10S