A fastener driving device for driving a fastener into a workpiece, comprising: a device body including a primary housing; a cartridge containment system mounted on said device body to load and unload at least one gas cartridge; a valve system mounted in the device body to receive and control pressurized gas flow from a gas management system; and a drive engine mounted in the device body to receive and control the pressurized gas flow characterised in that: the gas management system is positioned in the primary housing adjacent to the cartridge containment system to receive unregulated compressed gas provided by the at least one gas cartridge and to manage, regulate, and direct regulated and unregulated flows of pressurized gas; and the valve system comprises a low pressure lock-out system, said low pressure lock-out system comprises a lock-out pawl engageable with a trigger valve stem and the lock-out pawl is configured to prevent movement of the trigger valve stem when the lock out pawl is in engagement with the trigger valve stem; a lock-out pawl plunger coupled to the lock-out pawl and the lock-out pawl plunger is positioned in a bore between a first interior volume and a second interior volume, the first interior volume having a regulated gas flow pressure and the second interior volume having an unregulated gas flow pressure; wherein movement of the lock-out pawl plunger is determined by differential pressures between the first and second interior volumes (528a, 528c). a device body including a primary housing; a cartridge containment system mounted on said device body to load and unload at least one gas cartridge; a valve system mounted in the device body to receive and control pressurized gas flow from a gas management system; and a drive engine mounted in the device body to receive and control the pressurized gas flow characterised in that: the gas management system is positioned in the primary housing adjacent to the cartridge containment system to receive unregulated compressed gas provided by the at least one gas cartridge and to manage, regulate, and direct regulated and unregulated flows of pressurized gas; and the valve system comprises a low pressure lock-out system, said low pressure lock-out system comprises a lock-out pawl engageable with a trigger valve stem and the lock-out pawl is configured to prevent movement of the trigger valve stem when the lock out pawl is in engagement with the trigger valve stem; a lock-out pawl plunger coupled to the lock-out pawl and the lock-out pawl plunger is positioned in a bore between a first interior volume and a second interior volume, the first interior volume having a regulated gas flow pressure and the second interior volume having an unregulated gas flow pressure; wherein movement of the lock-out pawl plunger is determined by differential pressures between the first and second interior volumes (528a, 528c). the gas management system is positioned in the primary housing adjacent to the cartridge containment system to receive unregulated compressed gas provided by the at least one gas cartridge and to manage, regulate, and direct regulated and unregulated flows of pressurized gas; and the valve system comprises a low pressure lock-out system, said low pressure lock-out system comprises a lock-out pawl engageable with a trigger valve stem and the lock-out pawl is configured to prevent movement of the trigger valve stem when the lock out pawl is in engagement with the trigger valve stem; a lock-out pawl plunger coupled to the lock-out pawl and the lock-out pawl plunger is positioned in a bore between a first interior volume and a second interior volume, the first interior volume having a regulated gas flow pressure and the second interior volume having an unregulated gas flow pressure; wherein movement of the lock-out pawl plunger is determined by differential pressures between the first and second interior volumes (528a, 528c).