Your sensation of felt recoil, Rookhawk, was your body telling your mind you were right to think these loads were hot!
There was a time in the late 80's early 90's, before I owned a PC and "the web" was something I read about, when I was looking for low pressure loads and Kent Gamebore was pretty much the only game in town, along with Polywad, of course. At least that's the way I remember it.
Anyway, after RST came out and was on everyone's tongue I bought some and never looked back. I knew from shooting them they were a much lower pressure cartridge.
I strayed occasionally to test other waters. I've got a flat of "Westley Richards" 12 bore #6's I'd forgotten about until recently. I believe they were made by Lyavale, or some firm close to that spelling. To me, these seem hotter than the RST's as well. So did the B&P's someone gave me once, as well.
Hard to beat the RST's as far as I'm concerned, unless you reload of course. I prefer my cartridges to be sub - 7,000 psi, at least those I shoot in all my oldies, which is pretty much ALL I shoot!