A. For USP information, the best place are the forums at
www.hkpro.com.
B. The 10-round magazines have a known problem with base plates cracking. The problem is actually the wing on the baseplate (the baseplate has two tall wings, which prevent the following from coming down too far, thereby making sure the capacity is only 10 rounds). The problem is even worse for the magazines with extended baseplates (little finger grip), as are shipped with the USP Expert and Elite, because the longer baseplate has even more lever arm to shear off the wings when it hits the floor. The problem occurs most often when dropping loaded mags (heavy, in particular in .45ACP) on a hard floor. Like the concrete floor of the range where you are taking a tactical shooting class and practicing tactical reloads with full mags. I started the class with 8 or 9 magazines, and lost maybe half the baseplates during the class.
C. Reports of base plates breaking on full-capacity magazines (12-rounders for the .45ACP folk) are either nonexisting or very rare. The problem is common for 10-rounders. Which is little consolation for people like me in California, stuck with 10-rounders. On the other hand, I got a lot of 10-rounders for cheap after the federal AWB expired, and people in other states were upgrading like mad, and dumping their 10-rounders used on the market.
D. Replacement baseplates are easily available, for about $6 a piece, for example from OPS2 a.k.a.
www.hkpartsonline.com. As the gun and the mags have a lifetime warranty to the original owner, H&K will also replace the baseplates for free if they break, and you didn't buy the magazines used.
E. The .45ACP magazines have another problem: the mag bodies are bent out of a piece of sheetmetal, and welded in the back, along a cut line that holds the two pieces together like a zipper. The welds along the zipper can crack if a loaded magazine is dropped on a hard floor; then the magazine will open up like a squished banana, the feed lips spread, and it doesn't retain rounds any more. Unfortunately, replacement mag bodies are effectively not available as a spare part (the spare part costs more than a whole magazine). Again, for the original purchaser, H&K will replace the mag bodies for free. This does not apply to the new 9mm magazines (which have plastic bodies), don't know about .40S&W.
F. Let's get back to the Ferrari analogy. You just bought a Ferrari. Are you going to gripe about the fact that wear and tear repairs are a little expensive? Our neighbor supposedly paid $14K for the new clutch for his Ferrari. If you wanted a car that was cheap to maintain, you should have bought a Honda Civic.
The way I look at it is this: I'm shooting a gun that is very accurate, totally reliable, and has a good trigger (I have the match trigger in my USP). The gun itself was expensive (over $1K once everything is said and done). I'm taking a $400 tactical shooting class, and will go through about $150 worth of ammo during the class, not to mention having to practice before the class, and having to buy lunch. Now going and griping about having to spend another $30 on replacement base plates, and/or spending an hour packing up a few busted magazines for free repair at H&K is silly. And I can't see how someone's survival could depend on base plates breaking during training.
This having been said: for a gun that is as well-engineered as the USP, they could have done the 10-round baseplates better.