Components are made overseas than transported to the US. Same reason cars were sitting in parking lots waiting to be finished around the US as there wasn't computer chips... the computer chips are made in other countries. Just like Europe doesn't have the capacity to supply their own energy.
I have no idea what you are talking about, many countries outsource their military components... heck, the US outsources its services to get military equipment from one spot to another. So what? Much of what the US does is outsourced to third party companies, countries and civilian personnel. I take it you were never in the military?
The end result will be the same to the Ukraine... all this strange discussion isn't going to change the result.
All countries are involved in globalization, some more than others.
I doubt any country can turn on artillery shell production at the rate they;re going through them (people don't just leave that amount of production sitting there), which is why many countries in Europe have already said they have gone through considerable supply. So what? Make more, blow it up some more, make more, blow it up some more... until nothing is left. And everyone will than be happy.
Don't worry... if someone runs out... someone is going to produce it because everyone wants that crap hole gone.