[darkgael]

Some "specialty loads" in 12 gauge use plastic or hard rubber balls as crowd or animal control rounds. I tried to duplicate such a load - for chasing bears off the deck behind the house. I took apart a factory load that used hard plastic "buckshot". I measured the shot and weighed them and then weighed the charge and took a long look at the wad. I was able to duplicate the load at way less than they normally cost. They are as safe as I can make them and exhibit no odd behavior.
The military loaded 12gauge hulls with flechettes (small darts) for use in jungle warfare. They may still use them.
Pete