To answer your question: The shoulder mounted gun is an old toy a friend gave me to use in my costume. He knows of my love for Gatling guns. <3 He tells me it's not actually a Nerf gun though. It's some other brand of toy gun, and it's vintage from at least 1980, if not earlier. He got it second-hand himself, so he wasn't sure. I've never seen another one like it, it's a very unusual toy.
The arm gun is actually made from scratch - from PVC piping, motor parts, and other random junk. ^_^
You can get them now as a "nerf" gun, it from a brand called "air zone" the model is called; "punisher gatling blaster" hope that helps Sweet picture cyborg, I recognised that gatling arm the moment I saw it good work!