I'm about to turn 50 and am starting to get a tinge of it in my shooting knuckles. My personal observation is that the lighter the gun, the harsher the recoil, regardless of what caliber it is chambered in. That is certainly true for any alloy J-frame, even the ones chambered for .38 Special. One of the 640 Pros, if the barrel is ported, might work well, but I'd lean toward a polymer frame auto such as the Shield stoked with standard pressure 9s. I have fired the Ruger LCP 380s and the LC9, and thought the recoil on the former was noticable, and the later was just not fun to shoot - trigger needs to be redesigned (I could actually hit a torso target at 25 yards with the .380, while I could not hit the broad side of a barn from the inside with the 9). In order to shoot a carry gun that doesn't beat your hand to death, the pistol needs to have a little weight to go with the choice of reasonable ammunition. For that reason, I'm leaning hard toward giving my M&P 45 a rest and going to an M&P 9 full size. For backup, I alternate between a G27 with 180 grain Rangers and a 640 in .38 with 147 grain Hydra Shok +P+. Neither is a very pleasant load in a small gun. The good thing is that in today's world, you've got a lot of choices.