The Daniel Defense AR-15 DD4 RIII Upper Receiver Assembly is built around a Cold Hammer Forged Government Profile barrel, a GRIP-N-RIP Charging Handle, and carbine length gas system, known to have a smoother recoil impulse, which adds to this upper's accuracy by allowing for quick but precise rapid fire. It features a lightweight RIS III rail—modeled after the revolutionary RIS II two-piece handguard developed for SOCOM—features M-LOK attachment for lighter weight while still offering M203 grenade-launcher attachment.