I have a real soft spot for the High Standard Flite-King riot guns. They're all-steel and built like a brick (out)house.They're mechanically very simple and reliable and cycle as easy as an Ithaca M37.
If I had to pick nits, one would be the "single action bar", which is (was) also used on the Ithaca M37 and many other perfectly decent riot shotguns over the years. The only other one would be that the cross-bolt safety is at the front of the trigger-guard, although that leaves the rear of the trigger-guard for the action-release, ala the Mossberg pumps.
A lot of PDs used them back in the 60's, 70's and 80's, and you'll still see some in service. The originals were produced from 63/64 until 77/78 when High Standard went under. The three most popular versions were the 20", bead sight, 6 shot (5+1) model 8104, the 18", bead sight 7 shot (6+1) model 8111, and the 18", rifle sight, 7 shot model 8113.
There have been several reincarnations of High Standard since the original company folded, and they've produced some copies of the Flite-King riot guns, although all the ones I've seen left a lot to be desired when compared to the originals.
Going price for the 8111's seems to run around $200-225, with the rifle sighted 8113's going for a bit more.
I have 2 8111's and an 8113 and wouldn't sell them for any amount of money.