I'd actually like to see AP bullets be more, well armor piercing. Make them able to pierce through light armor and damage the health or electronics beneath, while doing relatively little damage to the armors ability to absorb regular attacks.
This of course would not apply to tanks, aside from maybe a couple of small weak spots. Armor piercing is different from armor shredding and an infantry AP round shouldn't be able to pierce heavy armor, so it should be nearly as useless as a regular infantry round against a tank.
But we don't have any confirmation on which types of ammo we will have and what those different types will do. Until we have more information on the subject, I am just going to go with the assumption that we only have standard ammo.
In that case, regular guns should do little to vehicles and nothing to tanks. AV should tear tanks apart, not rifles and pistols.
Again, please no knives damaging vehicles, that hurts my brain to think about how stupid it is.
That is, unless the devs have a change of heart, put prone position in and let you crawl under a buggy and use the knife to cut the fuel line
that would be awesome.