ok, i love the idea of ballistics, a secondary weapon with a lot of punch but limited by ammo....brilliant!
after some testing, i have revoked my previous statements that missles and mines are useless. i have come to see how effective they can be, BUT this effectiveness, in my experiences, only happens in a jousting environment. a situation where you and your target are thrusting straight at each other, during these types of conflicts a few well timed salvos can end a fight very quickly. The only problem with this is that it's not all fights are fought in a joust.
outside of a joust missiles seem to either not show up at all when you fire them or they play tortoise to the targets hare. mines are similar, as they wander around like a lost puppy looking for their mommy.
my proposal is this:
Missiles: increase speed to cruise speed (350)...that's all, it shouldn't affect how it performs in jousts but it should help it be more useful in other situations. i know people hate references to modern tech, but current missles travel at supersonic speeds, so it seems fitting really
Mines: increase speed to thruster speed (200)...same as above, i visualize these things as a thruster with a payload on it
if this makes them a bit too powerful you could lower the universal ammo limit to something reasonable.
just some thoughts i had on a possibly simple remedy to increase effectiveness of the part they play on the battlefield.