The CT is SR101 which is more commonly known as 52100 a good ball bearing steel with no chromium. The impressive part of the Busse heat treat with the CT is getting an excellent hard good edge holding steel tough as well.

How they do that with the M6 and larger Swamprats is differential tempering where they leave the back soft and only harden the edge.
That is a very difficult proccess on a industrial scale and one that no other company is doing. Even just working with 52100 is very difficult as Spyderco ,a company who knows knife manufacture ,found out while trying some out on a limited run of (test Mules). They were going to make a bushcraft blade from it but changed to O1 after the Mule.

S7 is the opposite. It was a "shock steel" which is used for jack hammer bits and the impressive thing about the Busse heat treat is getting it hard enough to hold an edge. I thought it might be to soft before I got my first S7 knives but it turned out they had good edge holding although not quite what the Rats or Infi had. S7 was at least as tough as INFI and even tougher than SR101 though which makes it perfect for big knives like the DF's and Yard Guards.

It's also the reason the new Muppy is CPM154 ,because a small knife needs edge holding more than it needs toughness unless of course your HornDog <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />