"Take my remarks or leave them..."
I'll leave them in this instance.
The HK P7 series of handguns has an enviable reputation for reliability stretching back nearly 50 years and with a number of major US and international police organizations.
The biggest failure point of the P7 series hasn't been the precision fit in the gas piston (one would wonder if you only have this concern about handguns, or any other gun that uses a gas piston design, of which there are hundreds, if not thousands), but the firing pin retainer collar.
Unfortunately, when that breaks, it also renders the gun completely nonfunctional. But fortunately it's easy to inspect for.