When you're looking for Maxim Defense ingenuity in a new standard AR-9, the MD-9 is your answer. The MD-9 was engineered to fit the growing demand for cutting-edge AR9-style rifles for today's Military and commercial market. Every MDX features our free-floating barrel with our custom handguard for increased comfort and versatility. These handguards provide a monolithic-like upper receiver platform and M-Slot compatibility.