Use the following trick to shoot multiple shots at once from a semi-auto gun (for example, Gerehr 43 or MP40). When you are sprinting with one of these or other guns, rapidly click fire (default is the Left Mouse Button). When you stop sprinting,
continue to click. When you are done sprinting, the gun should shoot three round bursts very fast. If it is a machine gun like the Thompson, it will fire extremely fast.