M995 isn't legally considered armor piercing. I have some in my room. It wouldn't be my first choice in 5.56 for self defense, but monster hunting would have different priorities depending on the monster. I'm pretty sure hollow points are only illegal in New Jersey.
I think acquiring M995 is pretty difficult and going to cross legal lines, at least for the seller.
And then there's Illinois law.
Illinois prohibits the knowing manufacture, sale, purchase, possession, or carrying of any armor-piercing bullet, dragon's breath shotgun shell, bolo shell, or flechette shell. ... Illinois prohibits the sale, manufacture or acquisition and possession of exploding ammunition.
You'd have to use black tips to really hurt the Sidhe or fairies, because lead isn't going to do much to them. At that point you'd have an easier time hitting them with iron or steel ball beings for cost/round, to say nothing of availability.
In the case of black Court, even AP might not do much other than punch holes to degrade musculature functionality.
And walking around with Airsoft or bb guns is not going to draw as much attention or scrutiny or legal trouble as hollow points or legal/illegal AP.