So in theory, all of the above is correct. No, it isn't reliable to fire 40S&W in a 10mm semiauto because the cases fall too deeply into the chamber (seating on the case mouth).

However, with some models, if you load from the magazine, it WILL fire, at least with reasonable reliability. The extractor picks up the case and supports the rim during firing. So yeah, it fires, but yeah, it also beats the heck out of your extractor (reliability issues in your future).

So sure, it can work, but no, it isn't reliable and it will damage your pistol.