Forget my last post: Aparently people dont understand the laws of the MAC Cannon. Really. The MAC (Magnetic Accelerated Cannon) uses the Physics of Magnetisum to charge the Cannon. Using the Kinitic Physical Laws the MAC can do major damage to Armor. Plus: If im right, Doesnt Subspace use Magnetic Properties meaning No Shields? Making the Lucifer and Shivan Strikecraft Weak to their Weaponary?
Ehh...
What you said, it makes no sense.
Sadly, it almost does. You're wanting to say electromagnetism, I assume. I don't know too much about the HALO-verse, but I get the impression the MAC is either a giant coil/Gauss or rail-type weapon: In either sense, you're dealing with electromagnetism.
The part about kinetic energy is... poorly put, but true. Any super-velocitized projectle will impart a tremendous amount of energy upon its target, so long as it has mass.
The last part is... kinda wierd. I'm guessing you're going off of one of the CBanis which shows a field about the subspace drive. However, that's an active drive unit. A launched projectile will probably not be utilizing some sort of field to... whatever you were after. In short, the conclusion you came up with is really quite disorganized. A MAC gun would still be a viable thread due to the fact that upon impacting a shiled, it would assumably place a great amount of energy against the shiled, weakening it after each strike, etc.