Not sure about the larger calibre, but the DSTO have a working...

Not sure about the larger calibre, but the DSTO have a working proof of concept weapon and have had so for some time, thye have sucessfully fired 60mm rounds at High Pressure (mach 5/50) on a repeatable basis, I think they may be going to use the tech in the latest CTD for the AICW, they say it will have a high velocity grenade launcher and a high velocity rifle with recoil mitigation built into the weapon, so I believe this may be the first we see of the mach 5/50 tech, and the Oz DoD say that they will be using the advanced steyr,around 2010 to 2012, but when you look at some of the requirements for Firestorm, it would I believe need High Pressure to achieve some of the ranges they speak of, read here what Mr Falkner said recently, "MSI General Manager, Peter D. Faulkner, said: “We are proud to have been selected to participate in the MRD and arelooking forward to our continued involvement in the Mission Payload Module program as the Marine Corps acquisitionprocess evolves. We believe our weapons platform will offer significant advantages in range, area coverage, precision,and scalability over current non-lethal weapon systems.” “The Mission Payload Module - Non-Lethal Weapons System will provide a non-lethal counter-personnel capability to support missions requiring crowd control and will deny, defend and control area access while allowing the user to engage threats at standoff ranges and protect non-combatants.” I believe that if they are talking about a weapon that is scalable and allow the weapon to be used at standoff ranges then I believe it will be higher pressure than just Low pressure!