So I tried one method to solve K3.

Solution One

It basically involves taking every 192nd letter until you’ve got the complete message.

It includes the “?” as the last letter.

This is by far the easiest way to solve K3 that I’ve ever heard of and it works.

The interesting thing is that the “Q” towards the end that I thought was added by cryptanalysts is actually in the ciphertext in the middle.  This means that when comparing grids of both halves of the Copperplate that you can keep the wayward L or “Ricky” for a total count of 867 symbols/letters.

It also seems to indicate (at least by this method) that the “?” is included in K3 and the letter count for K4 remains at 97.

I’d like to try the other two methods just to be sure.