After a LEO career spanning over 40 years I've got a few riot guns:
1-Remington 31
2-Remington 870 long tube
3-Remington 870 short tube
4-Remington 870 specail built w/12" barrel and front and rear pistol grip, have appropriate federal stamp.
5-S&W 3000 long tube
6-S&W 3000 short tube
7-S&W 3000 long tube folding stock, pistol grip rear
8-High Standard long tube
9-Winchester 1300 long tube stainless marine finish
10-Winchester 1300 long tube blued
11-Ithaca 37 trench style police w/hand guard bayonet lug
12-Ithaca short tube marked "Cross P.D. (have no idea where this is)
13-Ithaca long tube marine finish
14-Ithaca short tube marked US, Viet Nam era w/ correct marking, serial number range, and correctly placed sling swivels.
15-Mossberg 590 w/hand guard and bayonet lug, former owner Biloxi P.D.

Some of these I carried on duty over the years. Three of them (2 870's and the Mossy) I bought at a police auction because they were there...and average price was $110.00. I might have missed one, not sure.