Hornady manual for 223 remington lists the rifle that the loads were tested for. 35 grain to 60 grain was tested in a 26 inch 1 in 12 twist, Service rifle in an AR-15 20 inch 1 in 9, 5.56 NATO a 20 inch 1 in 7 but maximum pressure is listed higher and chamber throat is longer. I would use care using the 5.56 NATO data unless rifle is rated for the rounds.