enclave assassin
First time out of the vault
As far as I know the armor piercing rounds appears to be most effective against the robots, but the rest of the foes are lightly armored that even the hollow point rounds could make mincemeat out of them. Of course EMP munitions are even better. Beside the robots, are there any other enemies that wear good armor and are actually affected by armor piercing rounds? Power armored Brotherhoods don't count.