The Interlock is a very reliable bullet. I've seen a few come apart over the years, but only when severely stressed at closer ranges. As an example, my wife once shot a 15-1/2" pronghorn at 100 yards or so with a 130-grain Interlock from a .270 Winchester. The buck was facing her, and Eileen put the bullet at the base of the throat. Instantly dead buck--and the remains of the jacket were found under the hide behind the shattered spine.
I'd say that bullet worked perfectly, even if it didn't end up looking perfect!
