The force a bullet will impact your adversary is equal to (or less than) the recoil you felt when you fired the round. It’s physics.
But the gun itself absorbs some of the recoil due to weight, and if it's a semi-auto, the recoil system. That's why a say, Kel-Tec PF9, has punishing recoil to some, while a full-sized 1911 has minimal recoil when firing the same round, though your adversary would likely feel no difference. If you could close your hand around a cartridge, touch it off, and completely contain the detonation so the projectile would go in a straight line rather than the case blowing apart in your hand, then I would say the physics lesson stands. The force YOU feel THEN is probably what your adversary feels. (Aside from the obvious wound pain)
Not trying to be argumentative, but I see this written all the time and it's always bugged me, so I'm stating my opinion. The OP sounds like he has impressive credentials, and he and anyone else is welcome to jump in to prove me wrong. I certainly wasn't a straight A physics student.