To discount the "anecdotal" experiences of people without data to refute it, itself is to say 'only what I believe is supported by hard evidence, exists' . That approach woulda prevented pretty much any advancements in any field. An open mind to the unproven is what facilitates learning more about it.
Chuck;
While what you say is all "Theoretically" true I am never-the-less for the most part unconvinced.
In a totally non-related illustration some years back I had a good friend, whom I never new to deliberately "Lie" tell me he got 5 MPG better gas mileage by removing the tailgate from his pickup truck. I have no idea as to how he derived at that figure, but am fully convinced that in his own mind, he believed it. Even though this "Theory" was firmly de-bunked in that the tailgate is running in the "Draft" area of the cab & produces virtually "NO" gas robbing drag, many companies promoted it & made many $$$$ selling mesh tailgates, to those who bought it.
If you go down to your local ammunition emporium & buy a box of 12ga SAAMI 1oz loads it will almost certainly be listed as having a 3¼ DE, giving a nominal 1290 fps MV. Most of these "Low Pressure" 1oz target loads having pressure in the 5-6K psi range will be sub-1200 fps loads. Certainly, they will have less recoil due to reduced ballistics. Another thing to be considered these "LP" loads as given in the loading manuals will have been assembled in new cases. The reloader will most likely be putting them in fired cases. Considering slightly enlarged case volume, possibly weakened crimps, a load that may well be running very close to it's bottom pressure limit for complete & adequatly efficient combustion, may very well fall short of it's stated ballistics. Thus "Until" I see evidence of two loads with X vs Y powders, loaded to "Measured" same ballistics & being fired by a group of experienced shooters under conditions where they can pick the difference without knowledge of which load they are firing, I am simply compelled to treat most statements of "Reduced Recoil" as purely anecdotal.
Incendentally, L Brown has "Quoted" Gough Thomas as "Quoting" a Major British Co (one which "Sold" shells) as running a Blind Test with a large group of shooters with two lots of shells, Slow vs Fast powder, & they "Unamiously" picked those loaded with the "Fast" powder as producing less "Felt" recoil.
"BUT" that would be those having the "Quickest Acceleration" would it not??
I know no particulars as to what actual powders were tested or just what "Extraneous" circumstances may have swayed their "Feelings".
At this point, lacking provable evidence to the contrar, I am still of the opinion that approx 98% of what one will "feel" can be determined by the actual measured recoil produced. This of course assumes all variations fired from the same gun, certainly differences in stocking etc, etc, between different guns can vary the manner in which that recoil is transferred.
Ps; Another thing which should not I think be ignored is the fact of the gun iteslf weighing so much more than the ejecta it is given somewhat of a "Flywheel" effect. While the shot is Accelerating down the bbl at a much varying rate, one feels recoil as one push. It will of course take some amount of variation in the rapidity of this push, to be detactable. Just as different people can have different senso smell, different peripheral vision etc, so can different people have different sensitivity to this "Push". I guess I can just "Count Myself Fortunate" in that if I find with a given gun I can comfortably use 1 1/8oz @ 1200 fps, then I can just randomly use loads that meet that criteria & have absolutely no need to "Sweat the Small Stuff".
