re: .223 vs 5.56 Hog Hunting

They seem to be working ok, other than I missed a damn hog Sunday. I just can't get a consistent grouping on the target (good enough for my liking). I'd rather shoot the 5.56 rounds but all I can find are the green tips or FMJ. I have been using Frontier ammo. Just trying to see if the .223 is more accurate or I just need to shoot different ammo. Thanks for the reply!