Well, good guess aside, actually it could also be a Challenger. In my first post I was under the impression that the challenger had a discernably different front sight from the nomad. After a little investigation , it seems I was only half right about that. The Challengers I was thinking of , have a ramp and a pinned FS on it. It would seem though that there are some that do have the same FS. So.. I'm not actually sure how to tell them apart. I do know that the Challenger was the replacement for the Nomad after it was discontinued due to manufacturing costs.
OK, quick update: the difference is in the grip angle.