I received my Type B Black Dragon a week ago, with a king arms 150% spring set.
Shoots pretty well with 0.28 Guarder, but has problems with slidelock after 50 mags through it. I advise people to avoid using it unnessecarily The WE mag cannot fit the co2 adaptor valves for TM mags, so i'm ordering a TM mag for that. I expect to use a HPA rig with it.
I installed the 150% spring set, but that made the slide too snappy, so i went back to standard springs. Didn't seem to give a power increase anyway.
I found out that the hammer spring housing is in plastic, so i'm fitting on a RS Colt