Well a MAC round would be too big and kill the whole map....but maybe it can be a mini MAC gun. This is very possible to implement I mean Fallout 3 had a mini nuke gun that doesnt do anywhere near the destruction a regular nuke does This could be a cool feature to put on a UNSC ship. It could fight in space and give ground support from above. It can help engage hotzones that friendlies are in closer proximity This would also benifit space combat for the UNSC vessel since it wouldn't need to tip the noose of the ship to fire at the planet