The late British shotgun guru Gough Thomas disagrees that the burn rate of powder does not influence our perception of recoil (which we typically refer to as "felt recoil".) He does so based on experiments conducted in the UK by British powder company IMI. The following quote comes from Thomas' book "Shotguns and Cartridges", chapter entitled "Weight and Recoil": (Note that Thomas uses the term "sensible recoil" rather than "felt recoil.):
"To demonstrate the influence of rate of burning on sensible recoil requires a prolonged course of scientifically controlled experiments, such as those carried out by IMI when they were developing their modern range of powders and ammunition . . . They involved the firing of many thousands of cartridges by a team of nine experienced shots of varying build, shooting under a wide variety of conditions with guns of different types, weight and boring. The cartridges were all loaded to give the same velocity to the same shot charge, though by powders of various rates of burning. The shooters did not know what they were firing but were merely required to give marks for recoil. They were unanimous in assigning the lowest recoil to the cartridges loaded with the fastest burning powder, the dynamical effect of which was checked throughout by electric accelerometers built into the stocks of the guns, and their conclusions have since been widely confirmed."
