Did you know that the Peters company made ammunition specifically for riot control for the Thompson submachine gun in the 1920s? And it wasn't rubber bullets, either - it was paper-wrapped snakeshot. The cartridges were actually longer than a standard magazine would accept, necessitating the production of a special longer magazine to fit them. That magazine would hold 18 rounds, and was specially marked as such. I took a look at a lot of 200 rounds of this ammo and one of the special magazines at James D. Julia, and was curious how it would actually pattern.
Well, the Peters riot ammo is rare and expensive, but we also had some WWII-vintage .45ACP snakeshot on hand and I was able to try shooting some of that. At about 8 feet it made a pattern about 18 inches in diameter (from a rifled Tommy Gun barrel), and did not cycle the action. It was only after filming that I discovered the proper way to use this ammo for crowd control: fire it into the pavement in front of the crowd, allowing it to ricochet up into the crowd at a lower velocity. It would be less lethal that way, but still a great way to lose an eye!