Pintle-mounted storm bolters are located on the outside of a vehicle and can be used by a crewman from an open hatch or by remote control from inside. They are treated as an extra storm bolter and may be used in addition to other weapons the vehicle can fire, so a moving vehicle can fire one weapon and the pintle-mounted storm bolter.
Pintle-Mounted Storm Bolter
Source: Codex: Imperial Guard (1999), p. 9