Here is a Quote from Chuck Hawks:
"Although the concept of a dual core bullet is shared with the earlier Nosler Partition bullet, the performance of the A-Frame and Partition are different. John Nosler found that to achieve quick kills on medium (CXP2) game, it was desirable for the front part of his Partition bullet to expand rapidly. The core of a Partition is not bonded to the jacket and recovered bullets typically retain about 65% of their original weight. The A-Frame's cross member is thicker and farther forward in the bullet, its jacket is thicker and its bonded core prevents almost all lead loss after impact. It is a tougher bullet that retains almost all of its weight after impact and penetrates considerably deeper. At least in theory, the A-Frame should produce a narrower and longer wound cavity than the Partition, whose crush cavity is wider and shorter."
Further - Hawk notes:
"I have not shot animals side by side under controlled conditions with identical caliber and weight Nosler Partition and Swift A-Frame bullets, but my impression is that the Partition, in appropriate calibers, drops thin-skinned game quicker than the A-Frame (not that the A-Frame will not do the job on CXP2 and CXP3 game). The A-Frame, in appropriate calibers, delivers the extremely deep penetration required for thick-skinned game more reliably than the Partition. Indeed, in Africa the A-Frame is considered one of the best dangerous game bullets and it is widely recommended for hunting Cape buffalo. Here in North America, the A-Frame is highly regarded for shooting moose, brown bear and bison. I use A-Frames in my .338 Win. and .458 Win. Magnums and they deliver surprisingly good accuracy in both calibers, at least in my rifles."
I have tried Nosler Partitions in factory loads in my 270, 30-06 and 300 WSM and the accuracy out of these premium loads did not suit any of these rifles. They were clearly outside of MOA and were around 2" at best at 100 yards... That's not good enough for me so I use other ammo for those deer slayers...