Casey,
I suspect that many of your clients were using BT's they had on hand for a while--though the .338 has always had a very heavy jacket. The 180 .30 got a similar jacket maybe 3-4 years ago, and now works extremely well.
One of the odd ones is the 120 7mm. This got a super-heavy jacket before any other BT, due to frequent use as a silhouette target bullet. The early version broke up on steel and didn't knock those rams over consistently, so the jacket was really beefed up. I know a guy who's killed several elk with it from a long-barreled 7mm Remington Magnum, including some big bulls. He says he's never recovered one from a rib shot.
