Out of curiosity what chapter does she first make an appearance in, I wanted to hold off on project horizons until the main story was done so I would have to juggle the two but dammit now I've started reading.
"Vhat's dat sandvich? Kill vhem all? GOOD IDEA!" Awesome work! Nice to see you were able to do Lacunae justice, just like you did with Rampage. Also at Lex-The-Pikachu, I suppose a good way to rationalize why that monster isn't attached to a battle-saddle is because most saddle mounted weapons were made to be detached. Makes sense that if anypony using a battle-saddle mounted weapon ever needed to perform maintenance on them.
I believe most battle-saddle weapons are fitted such that the barrels end in front of where the wings would pass while flapping. for high caliber weapons, they would ideally be forward of the ears as well. fun fact- the A-10 slows down slightly while firing its nose cannon. this implement was torn from a robotic tank, I don't think a Pegasus (or any pony for that matter) could carry or handle firing one of these. Due to recoil and weight balance, it would be easier to shoot two at once, but obviously would be impossibly heavy. Levitation or mounting it to a fairly substantial platform (like the tank it came from) are the only plausible ways.
the Enclave power armoured soldiers have their weapons built into the armour. the antenna like beam weapons, that is their battle saddles, huge weapons like the minigun battle saddle were Earth pony orientated, the Enclave is high tech, the minigun and other projectile weaponry is likely low tech