Phil Shoemaker, the well-known Alaskan brown bear hunting guide, has done extensive penetration testing, sometimes on beached whales. He's found that the 220-grain Partition penetrates deeper than any other expanding bullet he's used, and Phil has used cartridges up to the .505 Gibbs, and most of the premium bullets made in the U.S.
My personal experience, both with various kinds of "media" and on 100's of animals in North America, Europe and Africa, is that the Nosler Partition is one of the deepest penetrating bullets made. It typically penetrates more than several other bullets that cost more, and more reliably as well.
Especially deep-penetrating are the heavier, larger caliber Partitions from 9.3mm up, which are designed to retain around 85% of their weight, rather than the 65-70% of sub-.30 caliber bullets. The medium sizes (such as the 225 .338) are in between, designed to retain around 75% of their weight.
This year I took about half my big game with Nosler Partitions. The list included animals as mundane as whitetails and as exotic as Nyasa wildebeest and Cape buffalo. The obsolete old Nosler Partition worked perfectly every time.
In fact I've used just about every expanding bullet made in North America, Europe and Africa, and have yet to find one more suitable for all-around use on a variety of big game than today's Nosler Partitions. In addition to working great when they hit animals, today's Partitions are also very accurate.
