They're coated in "Lubalox", which does essentially the same thing as Moly. Otherwise, they're basically like any other ballistic tip bullet.
Lubalox is a super secret name for cuprous (or cupric, I can't remember) oxide.
Cuprous/cupric oxide does absolutely nothing for the barrel and is a chemical treatment, unlike moly, which is a surface treatment. For all intents and purposes, the Lubalox coating is strictly a marketing venture that has absolutely nothing to do with any enhanced performance and is purely an aesthetic aspect that puts the CT projectiles as different than a standard copper jacket.
I think the older BST projectiles had a more moly like coating, but that was in the initial phase of them - for the past decade or more it is just a chemical treatment CT uses to essentially color the projectiles for marketing. They do have a wax like coating that is for corrosion/discoloration resistance, but outside of that they are no different than a regular copper jacketed projectile (as in no special cleaning procedures required after shooting, etc.). Lubalox does not build up in barrels like moly will.
As far as a "gimmick", no, the projectiles are not a gimmick. They are extremely good hunting projectiles that are accurate, consistent in weight and do their designed job extremely well when the shooter uses them within the limitations of the projectile and caliber.
I use them exclusively right now for hunting and have nothing but praise for their performance out of my .223, .243 and .30-06 on everything from light game (.223) to white tail deer (.243) and elk (.30-06).
Here is an example of a .243 exit wound on a little central texas spike shot at about 110 yards - 95 grain CT BST, 40.5 gr H414, Winchester LR primer, Winchester brass (not the greatest picture, but exit wound was about the size of a quarter)