The latest version and the version before it will have:
- stainless steel nozzle
Older than that version may not
The only differences between the latest version and the one just prior are:
- small screw on the face of the forward assist mag
- black hopup rubber (looks kind of dim/smoke grey when it's on the inner barrel...need to disassemble front end to actually see it)
There may be some other small difference(s)....but they'd be so minor that I didn't notice.