Ctay, I was curious about this issue as well so I asked for some first hand experience, no one posted any but I did get this article from 56hawk and did my own experiments trying to replicate the issue:
I send my slide off for milling work, so I've haven't fired any more .40 through it, but I did do an interesting experiment with a .380 case which made it's way into my 9mm loads: it was a light steel load (3.15gr Clays under a 115) so I figured I'd shoot it and see what happens
It chambered fine and I could see the rim was securely behind the extractor so I shot it; it sounded funny as the brass fire formed to the chamber, but when I extracted it I could see what this article warned of: there was a scratch in the rim where it pulled past the extractor with the primer ignition then it was slammed back into the breech face, flattening the primer against the head stamp.
Granted, this is obviously less likely to happen with 40/10 because the rim is exactly the same, but I can now see how it could happen.
I've shot 40 in a 10, 9x19 in a 9x21 and even 380 in a 9, never 9x19 in a 38, but that's because I don't have any 38s. Yet.