Ammo that penetrates class 1 armour
64 rounds14 calibers64 rounds are rated at class 1 or higher on the patch 1.0.0.142.19 chart — 17 exactly at class 1, the rest above it. Against class 1 plates these are the rounds that go through rather than get eaten.
Best per caliber
Every round rated class 1+
Not yet recorded for this patch: Price
What the class rating means
Armour in Arena Breakout: Infinite is class 1 to 6. The chart rates each round by the highest class it reliably penetrates; a round rated class 1 is expected to go through class 1 plates and below, and to be stopped or heavily reduced by anything higher. Durability matters too — a plate that has already taken hits stops less.
To see what a given weapon can load, open its best-ammo page from the weapons index; the full chart with every column is the ammunition index, and the plates themselves are under armour.