Matador Arms is a Veteran owned firearms and accessories company based in San Antonio Texas. They are most known for manufacturing 9mm uppers and supporting parts including magazine adapters and folding stocks. Matador Arms is the creator of the Montgo-9, a full 9mm upper that goes on an AR-15 lower. What sets the Montgo-9 apart from other 9mm uppers is the operating system. It features a non reciprocating charging handle, meaning it stays in place when fired. You can learn more about Matador Arms here. Shop Matador Arms here.