All Aluminum.

It is the BOMB! The end of the vent tubes at the tip can be chamfered and the ends of the vent tubes can be cut at a 45 deg./chamfered for a decrease of .4 second when filling a cc tank.
If it's leaking between the body and either of the end pieces check the condition of the o-rings. If the o-rings look bad replace them. If there good or new and it still leaks wrap some Teflon/plumbers tape over them and install it.
Leaking at the tip; soak the o-ring in some gas until it softens. If ya leave it in there to long it will swell! Install it back on the valve, assemble the gun. Leave the fill cap off and put it somewhere well ventilated. A couple of days later when the gas has evaporated out of the o-ring you will have an o-ring with a custom groove in it that will seal perfectly.
If it's leaking out of the vent tubes your over filling it or there cracked.
I know it's off topic the O.P. took us here...

the one i found is a plastic one/ anyhow i have a new aluminum kyosho one, but cannot find the o-rings for it anywhere, they were beat, so its new... any idea of the sizes or where to get a o-ring kit...looks just like the rb, except its black and reads kyosho,..

Look under seals or rubber in your phone book. Take the gun and o-rings with ya so they can size them. I use Florida Seal & Rubber Company.