David,
CTG was introduced back around 1995. A lot of nonsense spouted off about what it was/is.
Basically it is little more than regular 2Fg production that was heaved back into the polishing barrel for a little more polishing and a second coating of graphite. The additional rounding of the grains makes it look smaller than it actually is.
There was much wriiten about it on the various BP Catridge message boards. Some claimed it was a bit faster than regular Goex while others claimed it was a bit slower. Some claimed cleaner burning some claimed not as clean. They were simply quibbling normal production lot to lot differences in these powder properties.