A guy over on BARFcom posted this article in the great Ruger 556 thread. I remember reading this article when this issue of Precision Shooting magazine came out, but I was never able to find an online version of it. Well, here it is... http://technology.calumet.purdue.edu/met/higley/ExperimentswithHammerForgedBarrelsonAR-15s.pdf PS Make sure to read the "Discussion" section to understand why the 75gr. A-Max shot poorly (but still sub MOA!) from barrel #2.