Final answer:
The machine gun team member armed with the service pistol is usually the team leader or officer, who has the responsibility for command and oversight of the gun's operation and the team's defense.
Step-by-step explanation:
The machine gun team member who is typically armed with the service pistol is the team leader or the officer in charge. In the context of early machine gun teams, such as those operating the Maxim gun, the role of the team leader was crucial for command and control as well as for the protection of the gun crew. This member carried a service pistol for personal defense and as a sign of authority, while other crew members would handle the operation of the machine gun, including loading ammunition and managing its cooling system. Historically, during times of war, specialized weapons such as service rifles and machine guns played a vital role in equipping armies, and innovators like Hiram Maxim were instrumental in the development of automatic firearms that used the weapon's recoil to facilitate rapid fire.