Steve,
I know some of the instances were NOT early Ballistic Tips.
Nosler introduced BT's around 1985, and yes, some were pretty tender. This apparently was due to just sticking plastic-tips in the original soft-point Solid Base bullets, which were NOT very tender. I know this from me and Eileen killing a bunch of stuff with them, with bullets from the 100-grain 6mm to 165 .30. In fact, they were on the tough side; the few I recovered retained as much weight as Partitions.
But plastic tips tend to enhance expansion, because their shanks must be inserted into BIG cavities. Which is why many of the early Ballistic Tips "over-expanded"--though not all. But the problem was pretty quickly corrected by using a harder-alloy lead core, or a thicker jacket, or both. The 200-grain .338 Ballistic Tip, introduced in 1992, was the first with a REALLY heavy jacket, about 3/4 the weight of the entire bullet, and acted more like a Partition. I know this from testing them in both media and animals that year. (Today the same basic bullet is only available as the Combined Technology Ballistic Silvertip.)
I kind of doubt many of the original, "tender" Ballistic Tips were still around when the AccuBond appeared almost two decades later.
