Just got off a 20 minute conversation with Nosler. I called a friend who has worked at Nolser since the early 90's, he was busy so directed me over to another person (Mike) who is the Ballistic Tip guy, and was nice enough to answer my questions in detail.
I asked him about different jacket thickness in various BT's and how much they expand and how tough they are. He said jacket thickness is only a minor part of expansion, instead core hardness is the biggest factor in how much BT's expand, and every caliber and weight has a specific core hardness, and the hourglass shape of the core (see a cutaway of the Ballistic Tip), will vary to control expansion. The thickness of the base will also be specific to a bullet in each caliber and weight, and will be a factor in expansion. He also said the Ballistic Tip is not an elk bullet, and he does not recommend it for elk regardless of caliber or weight. He does recommend most of the Accubonds for elk, which he says expands slower than the BT.
Another tidbit I was not aware of is the Partition front and rear lead core are of a different hardness, and again the hardness of the two cores will vary with caliber and bullet weight, with jacket thickness being a small part of the expansion equation.
He was also careful to emphasized Noslers bullets are not drawn, but instead extruded. That's been discussed on here in detail before.
