No, the threads on the tube alone don't mate to any Surefire parts. You would need an adaptor.
The reason is an 18650 (or 18500) tube would not have enough metal left to support the threads at the head end if it's also wide enough to fully accept 18mm batteries. I think some may be doing this, but we won't. Therefore an adaptor is necessary. Currently we have adaptors that will fit our SF-Series heads and Aleph heads (Surefire E Series compatible) using TnC canisters (electronics). There is a fully E Series compatible adaptor in process and a C Series Surefire adaptor also in the queue.