I want an 18. I have 20, 14.5, and 16, but no 18s. I got a nice lower I was planning on building a nice gun out of, and wanted it to be an 18 inch. I didn't wanna go with a middy or rifle length gas system, though. I saw they also have intermediate length systems that are between mid and rifle, specifically made for 18s.

I wanted one for range, with a nice optic, and my 20 is set up as an exact replica of an 80's model m16a2, so the carry handle isn't removable. 18 is good enough, and it's a little bit shorter without much change in ballistics.

I got my 16 set up for midrange and my 14.5 set up for short-mid.