The Pig War was not actually a war, and the weapons that started it were purchased, not shot.
Nevertheless, when the Austro-Hungarians decided to teach Serbia a lesson, it was triggered by Serbia’s decision to purchase weapons from outside the Habsburg sphere of influence.
The weapons were French, not coincidentally a treaty-partner to the Russians, whose meddling in the Slavic Balkans had intensified as the power of the Ottomans waned.
The quick firing French 75 mm canon
To read more about the weapons that started the Pig War, please click here.