There is a major shortage of reloading data for the 5.56x45. I know...use 223 Remington data. It will work, but they are weak loads...the 5.56x45 is a hotter round...easily capable of going 1 to 3 grains over max loads for a 223 (depending on which powder you are using)...I have been working up some loads for my AR15 and will add them shortly. Every single one is well over the published max load for a 223 Remington. All have been THOROUGHLY tested...by me. Anybody else have any loads to share???