Welcome aboard!!
If you're not handloading, I'd recommend the winchester white box 45gr JHP, they're pretty much the gold standard for .223 Handi accuracy,
many handloaders have not been able to beat them, just equal em, 1/2moa accuracy is hard to beat!!! The Ultramax reman 40gr Nosler BT also shoot well, some like the Black Hills stuff too, but the WWB is real hard to beat and cheap too at $13 a box of 40 at WM.
Be sure to read all the stickys, there's a lot of info there that will help ya!! :wink: