of AA2520 under the 60 gr Partition or the hornady V max, in a 556 chamber, and SEE that it gets 2650-2700 fps, in warm weather, no problem, depending upon the barrel. The 55 gr white box Winchester is 2650 fps out of the 11" barrel, too. That stuff aint even loaded hot, either. It's 2950 fps out of a 16" barrel. Just because some ignorant bozo THINKS that you lose more than 70 fps per inch of barrel doesn't make it so.