Units that use miniguns/rotary cannons should have a higher attack amount (times the opposing units are hit by an attack). Considering these types of weapons typically spew bullets like fire hoses, it's strange that they only hit 3-4 times, with some of those hits deflecting or completely missing.
For balance, the offense/accuracy could be kept low, as well as the damage to respectable levels, but up the hits dramatically.
This change would strengthen these units to be a larger threat to unarmored units.
Some examples (Max Rank):
Heavy Gunner: 13-16x4 -> 13-16x8
Basilisk: 31-43x4 -> 28-35x10
Mega Tank MGs: 37-46x3 -> 25-32x6
Damage values could obviously be tweaked, but the key is to make it feel like you're really spraying the field with a hail of bullets by using these attacks.