[Mr.Unique]

It looks like former Marine is ok.

http://www.deseretnews.com/article/645197208/Excuse-us-Marine-is-not-an-ex.html
http://www.answers.com/topic/ex-marine
http://www.answers.com/topic/former-marine
http://usmc.tribe.net/thread/ced5fab3-d3b0-4291-ae53-7019382f6f50

I wonder if any of the folks who spring on this on FR threads are, or ever were, associated with the Marine Corps.

[cll]

“I wonder if any of the folks who spring on this on FR threads are, or ever were, associated with the Marine Corps”

In my case, I am a retired Army officer. In my civilian job I have an employee who served in the Marine Corps and he calls me “Sir” as long as I address him as “Marine”.

[USMCPOP]

Then there's Forever Marines ...