You must follow load data published for the 5.56 NATO, available from your favorite powder manufacturer.
Lee Pro1000 progressive 3-Hole reloading Kit for 223 Rem. Includes press, PaceSetter 2-die set (Full Length Sizer, Bullet Seater/Crimper), 3-Hole Turret, #4 Shell Plate, Auto-Drum Powder Measure, Short Charging Die, Universal Case Feeder and Small Priming system. Note: This press may be used to load 5.56 NATO (5.56 x 45mm) brass.
This press only accepts the 3-Hole Turret.
Pro1000 pictured mounted to the Lee Reloading Stand, sold separately.