I went through the hole thing gas tube and everything. Funny thing is the fail zero bolt when I got home went right into battery. But it’s outside in the snow as of now.Looks awful dry to me.
Won't go into battery is a sign of misclocked barrel extension, improperly aligned gas key or gas tube.
Have you inspected the locking lugs for impact/wear marks on the corners?
Have you checked the under side of the gas tube ( the part you can't see looking at it from the bottom of the upper?)
Is your front sight post cocked to one side?
Will it push into battery by hand with the upper broken open?