Well they pushed the partition forward so automatically it retains more weight. I have never seen or heard of a partition losing its rear core but remember this bullet was designed by the folks who designed the failsafe and maybe they just threw that into the design to differentiate it from the regular partition. My experience in exactly 2 calibers(Big deal) shows the regular partition shooting better. I am guessing that maybe 10% more weight retention will not make a difference at all. More marketing BS and sales of the bullet(PG) shows it