Rifle used was a standard M4 with a 16" barrel. This time around we shot a standard FBI style gel block courtesy of clear ballistics with a 5.56x45 mm. This was a 55 grain frangible round manufactured by Sinterfire. Our frame rate was 80,000 frames per second and the velocity of the round was around 2950 feet per second. It seems that we have captured another instance of sonoluminescence, which accounts for the brilliant flash of light as the temporary wound cavity collapses. We hope you enjoy it. Please comment, subscribe, and let us know what you want to see next!