plastic bullet 
noun
A bullet made of PVC or another plastic material, typically used by security and police forces for riot control.Rubber and plastic bullets are used for riot control by security services and police worldwide....
- Faced with escalating riots, the Italian police unleashed water cannon, plastic bullets and 12-inch truncheons.
- The Association of Chief Police Officers shares his reluctance to use plastic bullets and water cannons - which to date have never been used in mainland Britain.