That's a lot of rounds indeed, and with good care I don't see why it's not possible.

With my long range rifles I replace the barrel every 1200-1400 rounds depending on how it's degenerated, and the calibre. I always have a bore scope put down forst though, no point wasting money right? I am so familiar with what my long guns will do, how they perform, that I know when it's time for a new barrel. I'm not one to like inaccuracy, to much counts on the shot impacting its intended target, so I take some time to make sure my rifles are in top-notch shape.

With handguns I'm not so picky, although I certainly care for them. Having a firearm (or any tool for that matter) that doesn't perform when needed is the same as having no tool at all.

You mention H&K and I have to say I've always found them to be solid operators. That's just my personal opinion based on those I've used, but I think most would (generally) agree. I don't have one currently, however shoot na HK VP9 quite regularly and it's gratifying indeed.