Is your rifle chambered 223 rem or 5.56 NATO? Load based on the appropriate clambering. My Hornady manual has 223 rem, 223 rem service rifle( writeup says loads tailored for AR-15 chambered in 223rem. 5.56 NATO section cautions to only use these loads in AR-15 type rifles chambered 5.56 NATO. Be cautious as you go start low in the data and work your way up. Watch for pressure signs at each step of the way. Have fun shooting