mete, the Sierra 150-grain BTs and the 165-grain HPBT will really expand or blow up if driven above around 2,800 muzzle velocity and you hit something inside of 30 or 40 yards. Sorta like small hand grenades. The flat-bases have slightly thicker jackets and don't have the problem.
You're from BATFE? Come right in! I use all your fine products!