Oooh ooh ooh me me me!
I've owned several Kahrs, including the P40 and K40. There was a very noticeable difference in recoil between the two. The P40 had less recoil than I expected/was lead to believe from others on TFL, but it did have the most recoil of any pistol I currently own. It wasn't what I'd consider TOO much, but I wouldn't want to shoot often with a pistol that had any more kick than that. It was similar to my S&W 642 shooting .38 +p's.
On most range trips, I'd shoot maybe 20 rounds through it, then I was done and wanted to switch to something else. I have let less experienced handgun owners fire it, and more often than not, it got handed back after the first shot.
The K40 is just average in the recoil department. I could easily go 100 rounds with the K40 and still want to shoot more.
I have heard that the Wolff extra power recoil spring did a lot to reduce felt recoil, but I never got around to getting one to try it out before the P40 started acting up and I sent it back to Kahr.