No AR platforms here. In fact, I don't care at all for the AR style or platform. My 223 is of the target (100 yard benchrest) variety with a segmented ring 1.5" in diameter, scored on the ring, not the target itself, 10 targets to a sheet.
I actually shoot a very tricked out (by Accuracy Systems, International) Ruger Mini 14 target, setup to single fire, with no magazine.
BTW, I tumbled over 1300 rounds and boxed them last week. I'm not tumbling for shiny but for removal of any external deposits on tnhe brass such as case lubs that can carbonize upon ignition. After the final tumbling, I wear cotton gloves so as not to contaminate the cases when boxning them and I box in cardboard boxes with styrofoam trays
I worked up my load a long time ago and other than variations in powder lots, it's very consistent.