Better yet did you smelt the metal? If not there could be imperfections in it that could cause a catastrophic accident going down the road.
It's hard to have these types of conversations because at some point someone will say "Well that's just ridiculous, I should be able to trust the QA of the screw manufacturers." Just like how I've had some managers not trust the precision of resistors, and wanted each tested before, and after placement in the DUT (Dispite ICT likely finding these issues bringing up another FMEA). But what is ridiculous to some isn't for others. And at the end of the day my job can be made much more difficult than it needs to be depending on how ridiculous important people want to be.
Oh and the operating system, and drivers we are using are closed source as well. Is it ridiculous to make a new operating system, kernel, drivers, file system, etc from scratch? Yes. Would some managers think they are doing the company a favor by calling into question the integrity of the operating system? Yes.