Ah, the Partition's early answer to the old expansion vs. penetration question... (because this is what we are discussing ;-)
About 30 years ago, I came to realize that I did not have the time to hand load, but I wanted better bullets than the usual "power point," "core lokt," or such, with which there actually WERE genuine bullet failures. So I developed the basic rule of thumb of hunting exclusively with Federal Premium and Weatherby factory ammo, which used to be unique in the market and truly the precursor of premium factory ammo in as much as they were loaded with Nosler Partitions, the premium bullet before "premium" bullets existed. Further, I ended up making the rule of always using the heaviest Partition available to get both rapid & reliable expansion of the front core AND deep penetration of the heavier rear core.
This served me well, and continues to serve me well, on all sorts of game, in all sorts of places, at all sorts of distances with 6 mm Rem 100 gr; .270 Win 150 gr; 7x64 160 gr; 7 mm Rem Mag 160 gr; .300 Win Mag 180 gr; .300 Wby 200 gr; .338 Win Mag 250 gr; .340 Wby 250 gr; .375 H&H 300 gr. The lone exception to the "heaviest bullet rule" was to add the 150 gr Partition load to the .300 Wby when it finally dawned on me (duh!) that it is actually 2 guns-in-one with the 150 gr and 200 gr loads.
The Partition is not the new kid on the block anymore, it is not as fashionable as it used to be, and it is not the darling of the gun writers or guides or PHs as it used to, it is not sexy any longer, but make no mistake, it kills just as well today as it did 30 years ago.
Cut an A Frame and a Partition lengthwise, and the obvious resemblance is hard to deny. An A Frame is a Partition with a thicker front jacket and a bonded front core (I am almost tempted to add: period). As a result, the A Frame drives deeper but expands less. On the pro side it is useful on quartering shots on larger animals, as it gets you to the vitals more reliably. On the con side, a lot of the A Frame energy often gets expanded ... on the landscape after punching through with a classic lung shot on smaller animals. I like an exit wound as much as the next guy, no challenge here, but I also like the havoc that the Partition wrecks when it "loses" its front core in the vitals, which as
@PHOENIX PHIL rightly observed is not a failure but by design. The one thing I like in the A Frame is that because it retains its front core more, you can select a lighter bullet to have the same penetration a heavier Partition would after it sheds its front core (i.e. a 270 gr. .375 instead of a .300), but - there ain't free lunch - you will get less expansion. Some folks prefer the flatter trajectory and lesser recoil you get from the lighter slug. I personally was never really annoyed by recoil, and prefer heavier slugs that retain their flight path further, with the added benefit in the case of the Partition of delivering more expansion.
The Partition was a pioneer because it was the first to provide an "all of the above" answer to the question: do you want penetration (solid-like) or expansion (soft nose-like). Everything since then, from A Frame to expanding mono-metal slugs (e.g. Barnes) is providing its own variation of the same answer to the same question. I tend to not see a universal answer, but a buffet type of situation. For example: 200 lbs white tail deer? Prefer Partition. 1,200 Eland? Prefer A Frame. Quartering following shots on a running away buff? Prefer TSX (or good old-fashion solid). Etc.
The one MAJOR thing that seems to be often missed in this discussion is the issue of material. Here in Arizona, lead core bullets are now illegal to shoot in Condor areas. THAT is a unique differentiating characteristic for Barnes etc. Never saw a TSX do anything I did not feel 100% confident a Partition would not do, but a Partition sure does not qualify in lead-free areas... And if you have ever seen a radiography of a lead bullet fragmentation/vaporization in an animal shoulder, you kind of shake your head at feeding it to the grand kids. Us old folks are too far gone to care about lead ingestion anymore, but reportedly we should avoid it with the youngsters...
