My eyes caught the harness Calamity wore. The pegasus had twin long-range rifles, one strapped to each side of his body right under his wings, built into a saddle mechanism. Thin metal "reins" reached out in front of him, ending in a bit that hovered a few inches below his mouth. By biting on it, the sibling barrels would fire at once. The saddle was designed to reload on command -- possibly triggered by pulling on the bit, or biting differently. I couldn't tell.

Fallout: Equestria Chapter 5