Nosler 300gr .458 Partition load data

I have in my possession what may be the last unused box of .458 300gr Nosler Partitions left on Earth. In saving them for a special occasion, something requiring more penetration than your average whitetail.

Anyway, I took a look at the load data included in the box. Nosler says this is for "strong actions only," ie. above trapdoor levels. For IMR4198, which is my powder of preference, they list the load range from 35.5 - 39.5gr, velocity 1581 - 1739 fps. Compare that to their current load data for the 300gr BST's: 47.5 - 51.5gr, 2022 - 2228 fps. My question is, why the huge disparity in load data? Anyone have an idea?

Thanks,
Brian

The .458 300 gr PT is indeed an awesome bullet for the 45/70. I load them with H322 for a MV of 2200 fps from the Marlin 1895G. Penetration is almost into tomorrow.
viewtopic.php?f=63&t=16497
I've got a stash of them and used one on a crop damage deer last summer. The blood trail was nothing short of amazing.
To answer your question, the PT due to its construction, creates higher pressure than a cup and core bullets.

JD338

JD:

Thanks for the reply. Nosler lists 46.5gr H322 as max, with a MV of 1775 fps. I suspect you are well above that load, if you're at 2200.

I understand what you're saying about bullet construction and increased pressure, but this data from Nosler just seems really low.