I have HK USP 9mm w Threaded bbl. It has never had hiccup with suppressor on or off. I had the 45 version and never had an issue there either. This design has been out 30 plus years. Is the USP line obselete? Or am I just biased towards them because of my experience with them?? Debating on getting the Expert in 9mm. Thks!!
A quick search would have shown a whole long crazy thread on the same thing.
Here is the TLDR since that's probably what you are wanting.
USP line works well.
USP is a nice old classic kind of like the H&K equivalent of a 1911
Lots of folks like them for nostalgia and collectibility.
If you like that design and want another to complete your set, go for it, no problem.
There are more modern designs that H&K has put out such as the P30, VP9, HK45 that address various ergonomics and trigger options and optics and other options.
The USP line is better suited to if you like it "As Is" and run it just as it came from the factory.
If you start thinking about lots of mods and this and that, get a newer one.
Prices have gone up on it so it's not as great a deal as they once were.
For me if I wanted H&K in a hammer fired, I'd be getting the P30LS and if I wanted the striker fired and optics, I'd be going with some of the Match/Tactical VP9 models.