Just to be clarify winchester offers the Ballistic Silver Tip (black coated bullet with a polymer tip - similar to the NBT as nosler makes it for them part of the Combined Technologies umbrella ) & the SilverTip a cup and core bullet (copper and lead tipped). Name is shared but different bullet designs. I know guys who use the silvertip for elk in heavy gr. for caliber offerings. Personally I wouldn't use either but each his own.

Winchester moly loads were Failsafe & Partition Gold. The CT bullets offered currently BT and AB's use lubalox coating like Ridgerunner pointed out.