Carbon steel 4140 that is used in barrel making is actualy harder than the 416 SS thats used in those barrels , the differance come in that SS is less affected by the massive heat and cutting action produced in the barrel so they tend to last a little longer. Also the SS barrels are less affected by harsh cleaners especaily if you screw up and mix two that don't get along likle accu-bore and Sweets !! the grain in the SS is also a little tighter so their is less fouling.
Now on the positive side if you hunt in extreame climates like the artic or the Sahara the CM barrel will not be as effected by the temp like the 416 , this is the reason that Kreiger is making a 410 SS barrel.
Some barrel makers use differant steels The Blackstar barrels are made from 17-4 which is harder than woodpecker lips and a major pain in the peepee to machine but it does resist the gass cutting that occurs in the barrel better than the other two. Lothar Walther uses a steel that they call LW23 that is also supposed to be very tough stuff and since Lothar Walther makes the barrels for Blackstar I assume its the same thing or very close , I've never been able to cut on one so I can't say for sure.
If your using a very high intensity overbore round then the SS would be the way to go but if you just using somthing like a 308 or the such the CM would probably give you just as good of service , the fouling shoulden't be any worse if the maker laps them the same as their SS barrels
