There's a wealth of info here for you, and a great bunch of guys & gals to get to know. Friends can be made here. Hmmmm....interesting question, but I don't see how stateside made vs. overseas made ammo could make a difference, as the strength of a gun lies in its steel. Good quality made foreign made guns, function just as well as stateside made guns.(Don't shoot me!!! Just expressing my opinion!!)
IMO it's in the QC standards of ammo makers. Most stateside mfgrs. have good QC standards and a lot of offshore makers do as well. I would question the quality of offshore makers that are beginning to make their mark on the market...namely Wolf(made in Russia). That's the first that comes to mind. Belloit is French made if I remember correctly, and they are ALMOST on par to the likes of Remington, Winchester, Hornady, etc.......but not quite, IMO.
Bulk foreign made ammo, especially from former eastern bloc countries, are suspect I believe, and I wouldn't use them.
Just my 2 cents worth, if that has any value to begin with.
But it's my opinion, & I'm unanimous in that. 
Wolf is the only foreign made ammo that comes to mind.