It’s been entirely too long since I’ve spoken German. Can these be shipped to the U.S.?
If you click on Ihr Warenkorb and then Liefer- und Zahlungsbedingungen, you will get to a pdf that has the export conditions in German, French and English. Hope that helps.
In their Terms&Conditions at http://www.frankonia.de/shop/service.html?sp=einkauf/agb they name an e-mail address for export inquiries: export@frankonia.de . Should be OK to write in English. As the article you linked to (ammunition for signal gun) has a note that legal restrictions apply (the red one), you’d best also specify in which specific articles you are interested in.
It appears to be sold out right now, by the way. 
I’m looking for the spare flares. At 119 euro I don’t know if I’ll get them (I haven’t had to use the ones I have) but I’d like to find out if they’re available at all.
This is related to this thread.