Bought a Vigilance, put a pilum and a taclaser on it, and it still won't use its FMR.
There must be something else going on.
Edit: Okay, so I was completely mistaken; it DOES use its FMR, but it never does it more than once per missile reload cycle. So it fires one burst, FMRs, fire a second burst, and then wait to reload. I don't know why it does that, but I'm assuming it's part of the AI script to help preserve missiles or some form of balance (throwing out 52 pilums on a vigilance; Or 156 in case of the archer all at once would be more than a bit OP.), .
I specced the Archer so that it would be able to constantly use its FMR without having flux issues, so this is a bit of an annoyance.