You are welcome Dingy. There is no official designation of middle carbon steel. I have one of those spears too. It sharpens pretty easily with a regular bastard file so it is probably heat treated to lower hardness than CS used on it's SK5 fixed knives like the Trail Master and SRK. Maybe that is what they were trying to get across. Back when that and the Bushman among others were released onto the market the whole market was less sophisticated about different steels and heat treats. They market products differently now and premium steels are listed as what they are. I doubt they would use what is essentially a made up name like Carbon V and they would use the steels name as what they use are considered premium steels. Some of these products are from a different time and still going strong which is more a testament to a quality product at a good price and not marketing. Just an opinion anyways.
Joe