Technical Field
The present disclosure relates generally to fastening devices, and more particularly, to an automatic fastening device drives double-headed fasteners. 
Description of the Related Art
Double-headed fasteners (or “duplex nails”) have been used for many years in applications where it is desirable to later remove the fasteners from objects.  For example, thousands of double-headed fasteners are manually driven through wood boards/panels when creating forms for a concrete structure.  The outer heads of the double-headed fasteners will protrude from the wood boards/panels for easy removal of the double-headed fasteners a later time, such as after concrete has cured adjacent the boards/panels.  Manually driving thousands of double-headed fasteners into wood boards/panels or other objects is very time consuming and inefficient. 
Power fastener devices, such as electric, pneumatic, and fuel cell types, have been known for many years.  These fastener devices typically include a magazine that is adapted to hold a strip of nails which can be driven one at a time as the strip is advanced through a drive head and engaged by a reciprocating knife or hammer.  These magazines are adapted to hold a single-headed nail.  Thus, workers are required to manually drive thousands of double-headed fasteners without the aid of a power fastening device. 
Currently, nail guns used to build homes and other construction projects are typically pneumatic.  A pneumatic nail gun has a long hose connected to an air compressor that provides the compressor air.  This hose must be connected to the nail gun at all times.  If the pneumatic nail gun is being used around concrete construction, there are many protruding rebars, spikes and other hard items on which the hose might be caught or punctured.  Dragging a pneumatic hose around a concrete construction building in which duplex nails are often used is dangerous and may result in damage to either the pneumatic hose system or the user. 
Another disadvantage of pneumatic hose nail guns is their limited power.  An air compressor must deliver compressed air through a long hose and the amount of drive power is limited based on the compressor pressure and the amount of pressure that can be held in the hose system.  As a result, a pneumatic system has trouble driving even 8 d nails. 
A duplex nail has particular technical issues for being driven a full depth of the first head because power can only be applied to the second head.  The driving force must be transmitted from the second head through the shaft and to the first head.  The head being driven to be flush with the top surface is not directly impacted by the driving hammer, but rather, the second head is driven. 
Accordingly, the inventors realized that it would be beneficial to have a compressed gas cartridge type of nail gun to drive a duplex nail.