I think of the 21 K series as a prototype. If it wasn't offered to the general public, it's hard to call it something else I suppose.
I guess to really get to the bottom of it, what we need to do is find out WHY the K-2 was called the K-2. Was there a reason? Was it a K-2 because the 2 meant is was the second one? It would make sense, because there WAS a KP-3, and they changed the 2, to a 3. Or was that just a natural progression after STARTING with a 2?
I was told they started with the 2. Therefore, there could never be a 1.... It's like the sniper II's. They started at serial number 2000 and worked their way up. Serial number 1500 - 1999 never existed. It's just how things were arbitrarily done back then. So we can't slap numbers to stuff if we aren't sure yet.
Definitely need to know more. But as I stated, if it started out as a K-2, it's kind of hard to find a K-1, but instead just a K-2 Prototype.