Littlebird 7.62 vs LMG 7.62

Why does the Littlebird 7.62 mini gun damage most vehicles, even patrol boats, while a LMG using 7.62 Tungsten ammo (to dissuade people from saying "it's not AP ammo") barely scratches anything?

Volume shouldn't matter either, if even one bullet hits from a Littlebird, it will deal damage.

Even the new Interdictor sniper using the .416 Barrett with "150 damage" whatever that is supposed to indicate, doesn't scratch a patrol boat.

Feedback would be to bring the Littlebird down to par with LMGs or change the mini guns to .50cal guns to keep some of the same damage in line with other heavy mounted .50cal guns.