I shoot the Hornady 68gr. HPBT's with 25.4gr RL-15. Average is 3,020 f.p.s. I am using L.C. brass and CCI Benchrest primers. Lee Factory Crimp Die. I would start at 24.8 and work up. The reduced loads for the Lake City brass is because of the thicker wall ie. less powder capacity, but I have actually seen some mil spec brass that had the same capacity as Rem or G.F.L brass. This is where you get the higher pressure of the 5.56 versus .223. Not to mention the chamber specs. Look for traditional pressure signs. I have used these to 600 yards and maintain .5 M.O.A. The 77gr Sierra HPBT's are better at 600 but at 300, these will do fine. I am working on a 2520 load and will keep you informed .gun)