Those DuPont booklets just say "pounds." No PSI, no LUP, no CUP.
So, feel free to interpret it any way you want to.
There were many lighter/slower loads being offered, but we all know the North American Nimrod's desire for the heaviest/hotest loads he can lay his hands on. I'm sure most of these old guns saw plenty of these 3 1/2 dram 1 1/4 ounce loads.
I recall an article by Bill Headrick on a high grade Parker Bros. Pigeon Gun, in I'm pretty sure,
The Double Gun Journal, where the PGCA research letter showed the purchaser wanted it targetted with a load much hotter then anything our ammunition companies offered. Hopefully some day I'll have the time to find that article.