Also most semi auto handguns chambered for 10mm can also safely fire the .40SW using the same barrel (there are exceptions to this rule), and can be rebarrelled easily to handle the .357 Sig.
Revolvers chambered for 10mm (primarilly the S&W 610) can handle .40SW right out of the box. This is not the case with the Ruger Buckeye Special Blackhawk which depends on casing length for proper headspacing.
I didn't know you could shoot .40S&W out of a 10mm barrel in a semi. Don't they headspace on the neck rim of the brass?
(PS, I just wish I got to shoot enough to answer some of these questions myself, drat it!!!)