I've never seen any problem with the 400-grain .416 Swift A-Frame, and it's worked perfectly on the buffalo I've seen taken with it. Haven't ever seen the 300 .375 used on anything that I can recall, but have seen the 9.3 fail repeatedly, perhaps because (at least for a time) Swift made it by swaging down .375's.
I also tend to give less weight to weight retention than many people do. It's only once factor in bullet penetration, and in my experience less important than frontal area. In general, the lighter Partitions will penetrate just about the same as the lighter A-Frames, and the heavier ones, with the Partition moved forward, will penetrate deeper.
