It's elemental, actually. A PT is made for the tip to expand and the base is made to hold together and give deep penetration. An AB is made to explode. The plastic tip is driven down the center of the lead and forces it apart. It opens up much faster than a PT.
The AB is made to mimic the expansion of a partition in a bonded bullet with a higher BC. I my experience, that is pretty much what they do. I have used them to shoot just about every big game animal that I have killed for quite a few years now--elk, deer and pronghorns here in the USA, and plains game up to the size of eland in Africa . I have never experienced the explosive expansion to which you continue to refer.
It is a well-known fact that a few runs of ABs fairly early on were not made to specs, thanks to a Nosler employee who made unauthorized alterations to the manufacturing process in an attempt to speed things up. Once the problem was identified and rectified, the problems disappeared.
Ben
Some days it takes most of the day for me to do practically nothing...
