I found a couple videos on YouTube claiming to show a Marushin M712 blowback pistol.
http://www.youtube.com/watch?v=KiDbaxB-nmM
http://www.youtube.com/watch?v=2uxAySZAefo
Here's a real steel M712 just for kicks:
http://www.youtube.com/watch?v=0arGVi2pwz4
I'm still glad I bought my HFC Mauser though. I should buy the Marushin one for its "wow factor", and keep the HFC for its "oww factor" (370+ fps).