The loud report generated by certain reactive targets used in firearms practice results from the rapid expansion of gases produced by the chemical reaction. This rapid expansion can produce a pressure wave perceived as a sharp, loud crack similar to, but often distinct from, the supersonic crack of a bullet. This phenomenon occurs when the energy released exceeds a certain threshold and the resulting atmospheric disturbance propagates faster than the speed of sound.
The distinctive sound profile of these targets offers immediate feedback to shooters, confirming successful hits at longer ranges where visual confirmation might be difficult. This instant auditory confirmation enhances training efficiency, allowing for faster adjustments to technique and improved accuracy. Historically, the use of such targets has evolved alongside advancements in chemical formulations seeking to maximize the auditory report while minimizing potential environmental impact. Understanding the underlying physics of this supersonic phenomenon is crucial for developing safer and more effective target designs.