Abstract: A Punch Assembly and the method of use thereof is disclosed. Also disclosed is. The device is designed to be accepted within the chuck of a powder-actuated tool. The device can create a hole in steel decking when the device is shot into the decking by a powder-actuated tool. The device is defined by a mandrel and a detachable punch attached to it. The outer diameter of the mandrel is greater than the outer diameter of the punch so that when the mandrel prevents the device from passing through the hole created by the punch. The punch has a generally cylindrical shape and a cutting edge forming a pair of tips on opposing sides of the cylinder in order to improve the quality of the hole formed in the decking.