The Hollow Humor round are a type of ammunition used commonly for sidearms and sub-machine guns with limited uses for rifles.
While it can't punch through body armor well, it does cause severe damage to tissue. When the round breaks the victims skin, it collapses and forms into a sort of hammer. As it travels through the body, it punches through bones, breaking them into little pieces. The entrance and exit wounds are not to large, but most of the damage caused is internal.
In comparision to Reply rounds, the Hollow Humor do not go throught cleanly, as they punch thier way through the body. In this way, it is like a Sarcastic round, though it does not tumble due to force but it s shape.