Welcome Aboard, Bow.
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When the Winchester White Box 45 gr. HP ammo was available, it was pretty much the standard choice for Handi .223 owners. Many experienced MOA or less with it. However, Winchester suspended production of it. Some have found other types of factory ammo that shoot just as well. Others have needed to do some reloading to duplicate the WWB accuracy.
All in all, once you find the ammo of choice for your rifle, MOA and even sub MOA is not out of reach for your .223.
My standard barrel Handi .223 has always shot Federal American Eagle 50gr. Flat Base hollow points as well as the WWB. Usually MOA at 100 yards, if I was having a good day. The Federals are still available, but usually do not stay on the shelves very long around these parts.
Enjoy your new Handi.