Active duty military may NOT CCW just based on active duty status!!!!!! Must have a CCW.
Exceptions to this are: Active duty personnel who carry concealed as a part of their everyday duties and responsibilities (and are issued a Badge and Credentials which grant them CCW status) on base/post (ex. Army CID, Marine CID, AFOSI etc etc). These active duty military LE agencies (and some Reservist Army CID, Marine CID, AFOSI etc etc who are on Title 10 status) may carry concealed nationwide on and off of US Government property under the protection of; the LE Safety Act, their respective command's regulations and The Uniform Code of Military Justice while on duty or in performance of their duties off govt property.
This means; standard active duty personnel (ex. Infantry, regular MP, mechanics, supply clerks, admin, field artillery, etc etc) CANNOT carry a concealed weapon on or off base/post. Just like private civilian citizens, active duty military must have: CCW permit. In addition active duty military must have PCS orders to a particular state which will recognize that CCW permit, MUST be out of uniform (Im pretty sure this is correct but not totally) and off post/base.
To go further, active duty members (except like those military LE listed above) may not represent the Armed Forces in any way while carrying concealed. So, if you happen to intervene in an incident, you are intervening as a PRIVATE CITIZEN ONLY (ex. YOU CAN NOT announce you are "US Army...... STOP!!!" show an military ID card like its a badge of some sort, expect/gain compliance or affect a custody of anyone breaking local state or federal law, and using your previously concealed firearm to do it.(you will violate that persons 4th Amendment Rights and Posse Comitatus if you do)
However, active duty military can CCW out of uniform off post/base and use a firearm for self defense!! Lastly, if you carry concealed on post/base and are caught you will be apprehended by MPs. If you are caught off post/base without a CCW you will be arrested and probably prosecuted. If you represent the US Armed Forces in a manner deemed only appropriate for LE while using the force of a firearm, you will be arrested and then prosecuted by Civilian and then later by a Military court and you most likely will go to state prison then fed prison. Don't do it.
I advise you research Your Local, State and Federal Laws concerning CCW as well as your home stations Local and State Laws, and then contact your local MP Station for; guidance and rules and regulation concerning the concealability of, transportation of and possession of personally owned firearms on and off post/base.
DISCLAIMER: The information above is for general purposes only. The author assumes no responsibility for misinterpretation by any reader of its content. The information related in this post is not all inclusive and may differ in some areas. Do YOUR RESEARCH BEFORE YOU CCW AND ACT WITHIN THE CONFINES OF THOSE LAWS.