Actually, from what I can understand the above gun is functional with Airsoft P90 gearbox & barrel attached to MP5 hop-up. I also believe he used a M16 magazine to feed bb's. The builder also talks about another SST Gas blow back gun built around a Maruzen VZ61 SMG so it sounds like a lot of work went into the build.
AEG vs. GBB SST Moritas -->
