After reading through the config I realized that the A-164's Shrieker AP rockets are not 'Anti-Personnel,' but actually 'Armor Piercing.'

As unguided rockets are typically fairly inaccurate weapons, the obvious first through would be to assume that AP stands for Anti Personnel, as rockets are more used as area of effect weapons. HEAT rounds *do* exist for (for example) the Hydra 70 rocket, but are less common.
HEAT warheads can be observed in the Hydra 70 in the form of the M247 4kg warhead, but are less useful compared to APERS and HEDP (as they do not require direct hits).

For clarity, please rename the AP rockets (in the weapon dialog, upper right) to "HEAT," or at least "AT" to prevent any misconceptions about the useage of the weapon.