Ok So When I first saw the ACR it was a few years ago on future weapons. But when they were showing it off they stated that the weapon would be able to change between the calibers 5.56 Nato and 7.62x39. But I just went to Bushmaster's website and it shows that it is only available in 5.56 and 6.8. What happened? I mean I'm going to guess that it's because the 6.8 is ballistically more effective than both the 5.56 and 7.62 Soviet round. But I was really looking forward to the Originally setup because Soviet ammo is more affordable.