It seems odd to think of a Sierra that way, Klik, but there's enough reports out there of not-so-good expansion that it does need to be factored in. So I agree. Plus, when I called Sierra, they sort of said the same thing.
I'm just going to use the Partition. It may not have quite the "shock" of the 200-gn Hornady's I've been using (or, maybe it will, I don't know)... but Partitions are soft up front and it should expand reliably. It did put that one deer down fast when I tried one a few years ago and the shot placement was not great, either.
Plus the truth is, most likely I'll be shooting deer at like 40 yards anyway <g>. Or 40 feet. There's just a couple spots that I routinely hunt that used to be beyond the "reach" of my .358, and now they aren't- which was the whole point of this exercise in stretching the legs of this cartridge.
The 200-gn Hornady is, in my opinion, a spectacular bullet for deer from a .358; I love it. However it's not a particularly accurate load in my rifle, and combined with the low BC, it was sucking at longer ranges... I shot a lot of the dang things in the last few months trying to convince myself otherwise, but it's just reality. A switch to 225's and suddenly hitting the 375-yard gong is near-trivial.
