josephm20 had the correct answer immediately after your post so I’m adding some other info for improving your gun lexicon. Glock’s model number system begins at 17 and there never was a 9, except in the sense that numerous Glock models are made in the 9mm caliber. As to the “Glock 18,” it is a select-fire handgun, capable of fully-automatic operation. There are many “war stories” surrounding it but it’s safe to say there’s likely never been one in the hands of more than a very few special ops Marines, if ever.
Thank you.
A Marine friend of mine tested the Glock 18.
I do not know if they ever bought any.