That's a tough question. Several things come into play on felt recoil. The
operating action of the semi will soften felt recoil a bit. A revolver weighs (usually) more than a semi. I've shot the 9mm in a revolver (remember the S&W revolver with those stinkin' little clips to hold the shells?) and I say that the 38 just barely edges out the 9mm (using 115 grain bullets), and the 9mm is a lot less than the +P. Of course, that's just my opinion. Both revolvers were snub nose w/ comparable grips. Neither were the ultra-light revolvers now being produced with titanium.

What I like about semi-autos is the recoil us usually straight back do to the action of the slide. Revolvers have no place to go except back into your hand, causing the muzzle to flip upwards more.