Boy,, this brings back memories. I remember reading about the Rhino system in SOF back in the eighties. If my memory serves me, it is based on the FAL type regulated piston system. You could adjust the gas flow to acomodate many types of ammo,,, it also eliminated the old system of "shitting where you eat" that the M 16 was so criticized for. Wish I had the bucks for it,,,,