Experience plays a great part into it as well, but let's also not discount the tried-and-true-but-fundamentally-real "everyone is different," especially when compounded with "every gun is different." Someone experiencing painful recoil may just have issues with the grip angle, size of the grip, shape of the grip, how it all fits together into their hands...my wife can't stand shooting my 9mm Glock 19, but she was having a blast with .357 Magnum loads in my uncle's Colt -- we've discovered, since then, that she just like the grip and angle of a wheelgun more than an automatic. I could probably get a .22 conversion kit for my G19, and she'd still find it uncomfortable to shoot. Just something about it doesn't "click" with her.

As far as women and recoil versus men and recoil? Never discount the heft of ego. I don't think it's necessarily an issue of every woman really feeling more recoil than every man, I think it's a combination of hand size and grip strength, overall weight, comfort/experience with firearms...but also, and perhaps especially, that a woman may just be more likely to complain about recoil making her uncomfortable. Given the prevalence of 45 vs. 9mm fights on forums and in gun clubs across the country already, how many of us know a guy that would actually be willing to say, over a beer after a range trip, "Man, that 9mm really wears me out!"

That's more than twice as high, possibly suggesting that the AP rounds of the Five-seveN caused many more through and through injuries and reduced the amount of soft tissue trauma the victims suffered.