I got the 223 bull barrel and just love it.
My pet load is Win. 55 gr. PSP , Over 22 gr. of IMR 4895 and Fed. 205 small rifle primers , It also likes the 52 gr. Sierra HPBT Match Kings .
Shoots just over 1/2 inch at 100 yards .
Like Quick said
Read the Sticky's , It will do wonders . And yes the gold standard is the Win. White Box ammo , Some like the lighter bullets some like the heaver ones .
It will tell you what it wants .