re: quantifying "felt recoil". It's impossible, too many variables, but here's a scholarly attempt by Dr. Matt Hall
https://www.researchgate.net/publication/223811001_Measuring_felt_recoil_of_sporting_armsThe issue is debated on Trapshooters.com regularly, and Neil Winston would strongly argue perceived recoil has nothing to do with fast vs. slow powder
https://www.trapshooters.com/threads/recoil-test-of-powders-part-2-winston.79801/ Here's one of the latest; Tim is an engineer
https://www.trapshooters.com/threads/recoil-aaaah-our-favorite-subject.834949/ and
https://www.trapshooters.com/threads/powder-burn-rate-vs-recoil.651777/ https://www.trapshooters.com/threads/perceived-recoil.493105/ Blame it on Wallace Coxe - from "Smokeless Shotgun Powders: Their Development, Composition and Ballistic Characteristics", 1931
There is another factor which makes the recoil of a gun feel different with different powders, even when they are loaded to the same velocity and that is the rate of application of the recoil. It will be remembered that this was pointed out under the discussion on Characteristic Pressure Curves where it was shown that some powders burn up very rapidly and reach their point of maximum pressure in an extremely short time interval. This affects the rate of recoil, for the gun will begin to recoil at a higher rate of speed when the powder burns at a higher rate of speed.
The time required between the ignition of the powder and the time it reaches its maximum pressure is much shorter than the barrel time. Any phenomena that occur during this initial short time interval is only reported to the brain as a stimulus and does not leave any time for reaction to the stimulus. The mind can therefore only retain a subconscious reaction to impressions received during this short time interval.
It would be very difficult for any shooter to fire one shot of one type of powder and compare it with one shot of another type of powder and definitely say which powder gave him the feeling of greatest recoil unless of course they were loaded under entirely different circumstances.
During the course of a day's trapshooting, however, the shooter may be called upon to fire 50 to 200 shots. During this period the effect of acceleration of recoil is accumulating and by the time he has finished all the events there is hardly any doubt that the experienced shooter
can readily identify peculiarities of differences of recoil that his subconscious mind had received from the accumulated impulses of each individual shot.
It should be noted that this was written in promotion of DuPont MX Smokeless, a Dense Multi Base Powder introduced about 1930. 25.5 grains was a 3 Dram Eq. and it was promoted as a 1 1/4 oz. Trap load. It was replaced in the 1954 with IMR PB.
