How can i replace or recreate the cocking mechanism on my nerf gun maverick?

Yeah, the pin is the only thing you need. A bobby pin is too weak. Think about using a hack saw to cut off the sharp tips of a knitting needle, or similarly thin object. After you've got some sort of pin thing inserted where it used to be, put soft things on the edges to make safe handles. Like dried playdough, clay, dishrags and ducktape, etc