Rich,
No disrespect taken,
I felt the Glock was the appropriate pistol meeting the criteria in the OP.
I would agree that the USP is more durable based on the available info on the DHS testing, as is by far my favorite pistol.
The topic may have stated 'most durable pistol' but the content of the post, to me seemed more like a search for A durable pistol. Based on that I suggested the Glock for the reasons stated earlier.
In any event, said pistol will probably not be going to the end of the earth and will more likely just be used for some paper punching.
-Pirate