Army's Aberdeen Proving Grounds, Adaptive Research Incorporated, Berkeley Research Associates, EWS Limited, Johns Hopkins University, Pennsylvania State University, Sara Corporation, and Sonic Development Laboratory. The end product was to be a kit for quickly converting an existing lethal weapon to a non-lethal vortex ring generator that could knock-down an individual or spray him with a dye, malodorous chemical, or incapacitating chemical. The kit, consisting of a nozzle with chemical reservoirs and belts of blank 40mm cartridges modified to detonate at pressures up to 100,000 psi (690 KN/sqN), was being designed for the Navy MK19-3. The 40mm grenade machine gun was selected because firing at 4-10 shots per second resonates with many body parts and causes a stronger impact effect. Single shot field tests performed without optimized nozzles led to the conclusion vortex rings were unsuitable for non-lethal crowd control. This conclusion was reached partly because knock down did not appear to be feasible at the desired range of , partly because of the excessive spillage onto bystanders under the flight path if used to transport chemicals or dyes, and partly because the flight noise and speed enabled it to be easily avoided at the downrange target. The foremost reliability issue with this project was turbulence caused by the high-energy propellant burning outside the barrel. Hail cannon Later commercial solutions overcame some problems of the US Army concept by using less energetic gas propellants through the re-purpose of the hail cannon which reliably fires vortex rings at one third the speed of sound or better. (Note that hail cannons have been in use for over a century and do not themselves qualify as "later commercial designs".) References External links Overview of the vortex ring gun program Live rifle fire and computer modeling of the muzzle blast vortex ring Engineering design of the prototype vortex ring gun Non-lethal firearms Vortices