Is this it? 40mm grenade launcher
http://fas.org/man/dod-101/sys/land/40-sponge.htm
Yes, we have them in the prison.
The round looks slightly different. It does come in 40mm.
http://keranews.org/post/dallas-police-try-sponge-guns-help-avoid-deadly-shootings
from your link:
Minimum engagement range is 10 - 15 meters, and maximum effective range is 50 meters.
The defendant was only 9.2 meters distant when he was hit by the massive 40 millimeter projectile!
This so enraged him, he could not stop to surrender and was forced to return fire with both the Mac-10 and 9mm pistol that he had just found on the ground, only a few seconds before being blasted at such illegally close range.
I think you’d need something in the neighborhood of a 40mm sponge projectile to even approach “incapacitation”. Anything near the size of standard firearm calibers would just make the perp angry. Perhaps only mildly annoyed.