Hey just figured this one out.

In the Halo books they say that the MAC Guns (magnetic accelerator cannons) on the the orbital defense platforms fire a 3,000 ton projectile near or about 1/3 the speed of light. Now I was trying to figure out something that weighs that much and I was reading through one of my BTech source books and I think it was either the Union or Overlord class dropship weighs close to that.

So If you think about it, Those MAC guns are dropship cannons





They have us surrounded again, poor bastards... - General Abrams.