Does anyone or current serving Marines know.?  Being a prior-service Marine, I had to get the new pistol, but want the official holster too. Thanks for the response in advance.

Using a little DuckDuckFu, I found these approved NSNs for M18 holsters.

5.O.  Pistol holster tan (rh shooter)/1095-01-676-6956/M18.
5.P.  Pistol holster tan (lh shooter)/1095-01-676-6823/M18.
5.Q.  Pistol holster black (rh shooter)/1095-01-676-6761/M18.
5.R.  Pistol holster black (lh shooter)/1095-01-676-6785/M18.

I follow the Marine Corps Shooting team on instagram, it looks like they're using the same Safariland 7TS ALS kit the Army is buying.

That’s what the interwebs say as well.

https://www.tactical-life.com/news/army-m17-m18-pistols/

Thanks for the help guys

The MPs at the main gate of Lejeune use black Safariland holsters for the M18.

I found this:  https://www.quanticotactical.com/product/safariland-m18-mhhaf-kit/

I ordered a OD light bearing holster, now I need to know which fast attachment I will need for a belt setup.  It cane with the black belt adapter but I want the fast attach setup.

Had a hard time figuring out which mag pouches to use until I found the link above.

For anyone running a Surefire or Streamlight with optic this is the holster:  
https://safariland.com/products/model-6360rds-als-sls-mid-ride-level-iii-retention-duty-holster-model_6360rds

Not sure if the Corps will require a suppressed holster?  This holster is heavy but seems jump-worthy and is the only recommended holster for hard use by reputable folks.  The 7TS is nice if you don't need a light or optic holster.

I have a safariland 6000 something holster and several 7ts type holsters.  I like the 7ts much better.  But i have the light and rds version.  The only thing i like better with the 6000 series is the multicam wrap.