I just picked up an AT-XC and was going to have Bugholes do a 223 conversion. I was able to find a complete bolt, but when I went to put it into the gun, it was a no-go. After comparing the two bolts, it is clear that the changes they made for the AT-XC are significant. Unless I am missing something, I will have to wait for the AT-XC bolts to become available.