I just went to
http://www.knightrifles.com/catalog.aspx?catID=NewProducts
And they have the designation for the one I bought (black & blue) as
KRB607C.
I reckon the KRB707C (composite & stainless) is the most popular model, therefore everyone calls it a KRB7.
Knight just lists them as KRB unless mentioning a specific variation.

But when I bought it, even the factory stuff for this specific rifle said KRB7, not just KRB. Gotta be a reason.