ThatZenoGuy
Residential Zealous Evolved Nano Organism
TBH, I always suppose a "fully functioning" power armor (especially those from Enclave or BS) would beat those raiders/fiends like this:
In Robo-cop lore, gangsters do beat him with a .50 (or M-60?) with AP rounds
But, in postwar fallout world, there's shouldn't be many (or any at all) tunsgten .50/5.56/7.62 AP rounds among most inhabitants, because:
1. Lead is easy to melt and mold, tunsgten is not.
2. Those AP rounds are shit for hunting, "softer" rounds like FMJ, or dumdum (expanding bullets) are way more useful for that purpose.
3. High caliber rounds are expensive. You should practice your shoot and use .22 for hunting and head shot you foe.
And that may explain why NCR beat the shit out of BS as NCR would have those high-end weaponry in their arsenal, including AP rounds.
NV shows us that AP ammo is commonly used, remember that AP will work better on metal armour and armoured mutants better too!