Description:
Xenonaut's weapon firing animations glitched when I was shooting a wall adjacent to my soldier.
What happened:
I was holding down Ctrl to force fire and destroy walls in order to breach buildings or ambush cleaners.
It happened with ballistic rifles, shotguns, machine guns, sniper rifles, and all firing modes.
Further Information:
Simply place a soldier near a wall, hold down Ctrl, and force fire it. It's almost always reproducible.