Get yourself the RCBS Precision Mic, for your 223. You measure the fired case, set up your full size die with a 7/8x 1/8 rubber O - Ring from your local hard wear store. First bring up the ram all the way on your press, screw your F/L die down to just touch the she'll holder lock your lock ring in position. Then remove the die put the o-ring under the lock ring, screw the die back into the press to just lightly squeeze the o-ring. Size your case , check the measurement with the fired case measurement . your looking to make your sized case .001 smaller then your fired case. The mic will do that & your OAL very easily. Will custom your sized rounds to your rifle. Are you using the rifle for only target shooting? All serious bench rest shooters have switched to F/L sizing not neck. Proper case prep. sizing, right bullet & powder charge, good shooting form. You should be getting that 5 shot 1 hole group. Keep up the good work . Hope I helped.