At the paintball size it’s now more common to see CS filled paintballs. Those don’t require a huge amount of kinetic energy to work, although exposure to CS gas has its own long term side effects.
To put that in perspective, try to make the largest circle you can make with your index and thumb (think OK symbol shape). That's more or less the shape of these things and they are effectively a thin layer of rubber with a solid steel core. The inside of your finger circle is the steel and the thickness of your fingers is the rubber.
Hope this helps.
40mm, about 1.5"
What "long term side effects" does CS have? The US Army (at least) routinely puts all soldiers through a CS filled gas chamber as part of chemical warfare training and has done so for decades.
eitland has been exposed to concentrated cs at least once, Anigbrowl multiple times including more than just once just this last week and it seems to be common in military training from what I read so I guess it is in fact well studied and reasonably harmless compared to many alternatives.
That said I agree with a number of people here that in most cases the best alternative might be to talk to people instead, and to not kill suspects in custody, obviously, and also to not handcuff and throw people on the ground when all that should be necessary was to ask simple questions.