I know the USP has been tested by lodging a bullet in the barrel and then firing a round behind it. Then they cleared the gun and it still shot something like 4" at 25 yards.
I watched a video of a women who worked at H&K, she pulled a P2000 polymer frame from a bin and proceed to pound on it with a hammer about 4 times. Not even a scratch.
They have frozen loaded USPs, taken them out, and with ice still caked about the frame, fired the entire magazine with nary a problem.