Okay, I've been wanting to know this. Alright, so Tokyo Marui's High-grade line of spring pistols have a fixed slide, and they are semi-automatic. I was wondering, how exactly does the spring reset? Is there a sear like mechanism to reset the spring? I would like to know.
They're not. They're air-cocking, so you pull the slide each time you want to shoot.
There are the Gindan pistols, which do have an interesting system for cocking the spring each trigger pull, but they can't shoot anything other than specially designed .12s.