I got it. They said they have blue label FN 509 Tacticals on order and they only 2 HKs so... And I know there are HK import issues. I like how you said "simply get some 17 rounders" like they're not an insane $50 per mag. That being said, I ordered a couple 20 rounders for more .As others have said and I did, order the 10 round H&K and simply get some 17 rounders on line. You can always use them at the range if you don't want them for carry. H&K has them in stock usually as does Grab A Gun.
I guess you could say, instead of waiting for a fullsize, optics ready XDM Elite , or even the 509 Tactical, I got what I could get (went from $ to $$$ though) but I don't think many would call my choice "settling" .