Here's my take on it, based on physics.
Muzzle energy, firearm weight and other factors being equal perceived recoil differences are a function of time.
The firearm starts moving rearward as soon as the bullet starts moving forward out of the case. It has to, you can't break the laws of physics. The bullet being lighter in mass moves faster and farther than the frame which has much, much greater mass, but the energy being stored in the mass has to be equal for both action and reaction.
The movement of the bullet down the barrel continues this action/reaction until the base of the bullet clears the barrel at which time both bullet and firearm have stored all the energy they are going to receive. The ejecta (gas and residue) that follows the bullet out of the barrel does have mass, but the total weight of the gas and particulates is miniscule compared to the weight of the bullet, so it contributes little to the recoil energy imparted into the firearm, and is likely offset by the drag of the bullet in the barrel.
Although the bullet is accelerating forward, causing the firearm to move backward the bullet is trying to drag the barrel forward with it due to friction in the barrel. So some of the rearward recoil energy is negated by bullet drag working against the rearward movement of the frame. There are many factors in play when you fire off a round. But most, like gas ejection and bullet drag, would tend to cancel each other out, and have only a minimal effect on the overall felt recoil.
So a faster bullet imparts all of it's reaction energy to the firearm over a shorter period of time than a slower bullet, resulting in what is perceived as a 'snappy' recoil. A slower bullet that produces an equal amount of energy spreads it out over a longer time period giving more of a 'push' perception in felt recoil.
A .357 loaded at max power with 125gr bullets will have a much snappier recoil than it does with a 158gr bullet loaded to the same power level. In a lightweight 12~14oz revolver with 125gr max loads the lack of mass in the frame results in it moving backward so rapidly, due to the short duration of the impulse, it may unseat the rounds in the other chambers. Using 158gr bullets will spread the impulse out over a longer period, as the bullet accelerates slower, and the problem doesn't occur.
The 125gr will also impact lower than the 158gr using the same POA. The heavier bullet takes longer to reach the end of the muzzle, so the barrel has more time to rise, and thus impacts higher than the lighter round which left the barrel sooner.
But that's just my opinion based on physics and practical experience......
