PhysDoc,
They said they checked headspace, it may be some DCM 03s/03A3s closed on a No Go gauge. The No Go gauge is .006" longer than the Go. If a bolt wouldn't close on a "Field", it was considered "safe" by the Government. Since the Field gauge was .010" longer than the Go, some DCM rifles likely closed on the No Go, but not on the Field, so were kept in stock and latter issued through DCM. AS always, I might be wrong.
Mike