I have shot both rounds in the same pistol frame before and the 40 has more recoil. The nine can depending on what rounds you use. If you are shooting +P defense rounds they can kick. But target ammo should not be that bad.

9mm and .38 are pretty close, and when you add the momentum of the slide I think a 9mm kicks a bit more than a .38. We used to shoot at an indoor range in passedena or LA when I lived in CA. I had a browning hi power 9 mm, my siter in law had a .38 feather lite and her husband had a glock .40. In order of recoil it was his glock 40, my 9 mm and then the small .38 revolver. And then my wife had the browning buckmark which was none existant for recoil.

Alot of it will depend on the weight and design of the gun, just like a rifle. I feel revolvers are louder though. However I have shot full frame .357 revolvers that felt better than some 9mm autos.

I would really say let her try some out and see what she likes before spending that kind of money. I would really suggest a .22 for a starter gun. They are a lot of fun and cheap to shoot.

Paul