Theoretical recoil is dependent on more than muzzle energy. Recoil in ft-lbs is basically the muzzle energy times the bullet weight (in lbs) divided by the weight of the gun.
I, as an engineer, and a friend that enjoys shooting and is a physics professor, independently developed an expression for the recoil of a gun. He use a totally different approach than I did and we got exactly the same results.
Er = Muzzle Energy X bullet wt (ozs or lbs) / gun weight (ozs or lbs)
Then a member that has a recoil calculator compared my numbers to his calculator values and we were within 10%.
Things that were not accounted for is slide mass etc, and no attempt was made to isolate muzzle flip.
I had been shooting 9mms for years, and finally bought a G22 (.40 cal). It was incredibly different than a G17. It was lifting, torquing, and recoiling significantly more than the G17. I was shooting range ammo in both.
Recently, I spoke with a guy that also shoots a lot, trains SWAT members etc. and he agreed 100% that the .40, in a given gun, has far more recoil and he mentioned torque, than a 9mm.
IIRC, using my formula, based on range ammo, the Glock 22 has about 50% more recoil than the Glock 17.
There is some confusion about this because different people perceive recoil differently. It doesn't mean the recoil isn't there or somehow got magically reduced of multiplied, it just means that two people 'feel' it differently. It also does not mean that the effect of the recoil was not present, it just means we don't realize it is.
Recoil is not something that changes just because one person feels it more or less than another. The recoil is constant, based on the muzzle energy, bullet mass, gun mass, and a few other characteristics of the gun. All that is transferred to the shooter. How much it affects the shooter is the variable.