Maxim M1910

In episode 10 from the second anime series, Roy Mustang has a flashback to the Ishvalan War of Extermination showing an Ishvalan resistance fighter engaging attacking Amestrian soldiers with a Maxim M1910 machine gun. It would later be revealed that was Aerugo that provided this and others types of weaponry to Isvhalans.

Trivia

 * This weapon is a Russian-adopted version of the Maxim, adopted originally in 1905 with a bronze water-jacket but modified and standardized to a corrugated-type jacket in 1910.