Your sense is almost certainly right.
Part of the problem, such as it is, with German guns is that they are precision machinery designed and made by Germans. As in "we are Germans and make quality things, so there is no need for us to worry about spare parts because even to admit spare parts might be needed would demean our skill and quality."
Why do you think the mechanics at the Porsche dealer wear white lab coats?
Then, when you need a spare part, not only are they hard to find because of scarcity but the mere act of asking for them can offend some of the craftspeople.
