While the world has moved away from it ...... the 9mm H&K MP-5 was king of the hill for years....

As a HD or PDW or urban SHTF gun I like my Beretta CX-4 with 17-20 (and 30s now) round 92 magazines set up w/ a 92 Centurion.

I've got a 300 lumen Streamlight on mine.......... it's good to go out to 75-80 yds. or so.

At 29 inches they are actually 3" shorter than a AR with the stock collapsed and weight in at only 5.6 lbs.......about a pound less than a AR.

A 9mm S&W AR that would take 569xx mags would be cooool given Meg-gar still makes 20 rd mags!!!!!!!!