An apparatus for dynamic testing by rapidly accelerating a test specimen includes a sled carriage slidably mounted on first and second elevated horizontal tracks attached to a fixed foundation for free movement of the sled carriage along the tracks from a first to a second track location; the sled carriage having an essentially horizontal mounting plate terminating in a leading edge at one end and a trailing edge at an opposite end; and impact block mounted to the bottom surface of the mounting place intermediate the leading and trailing edges; a pressure differential firing component having a moveable thrust surface for striking the impact block; the pressure differential firing component attached to the foundation between the tracks so at least a portion of the bottom surface of the mounting plate of the sled carriage between the leading edge and the impact block can override at least a portion of a firing chamber component of the pressure differential firing component; a high pressure compressed gas storage chamber attached to the foundation between the tracks in a position substantially parallel to the firing chamber; and manifold component fluidly connecting the gas storage chamber with the firing chamber whereby, upon actuation of a trigger component, gas in the gas chamber causes the thrust surface to strike the impact block whereby longitudinal movement is imparted to the sled carriage to cause propelled movement of the sled carriage from the first to the second track location.