The XM7 is soon going to be on the "failed" list, BTW. Initial feedback is that everybody hates it. Also the "penetrates Level IV body armor at 600 yards claim" is not only untrue, it can't possibly be true because it is physically impossible. If you consider the KE and momentum of 6.8x51mm at 600m, and consider the KE and momentum of 7.62x63mm +P at muzzle velocity, this should be trivially obvious. Tungsten and other new materials don't get around this energy gap -- and tungsten 7.62mm rounds are already known, and already fail against certain Level IV plates at muzzle velocity, to say nothing of 600 yards.