I came across this whilst randomly browsing through wikipedia:
http://en.wikipedia.org/wiki/Vortex_Ring_GunThe vortex ring gun is currently (as of early 2006) being developed. It fires a blank cartridge into a barrel which widens towards its muzzle. The pressure accelerates the air or gas in the barrel at high speed and it becomes a high-speed travelling vortex ring.
The weapon has been shown to knock down a 75 kilogram (165 lb) human dummy from 10 meters away; military use will need a range of more than 20 meters.
It is planned to mount the vortex ring gun on a GL-6 repeating revolver 40 mm grenade launcher, or on the MK19-3 automatic 40-mm grenade launcher.
Firing at 10 shots per second resonates with body parts and causes a stronger effect.
An incapacitating agent can be injected so it mixes into and is carried by the vortex ring.
I can see the possibility of having a ranged stun weapon, which would have a longer range than a stun rod, and more accuracy than a stun grenade.
