ceramic
supposedly, from what I heard it is to keep it cool and together, a la space shuttle due to the heat the firearm can generate.
I heard of a prototype that uses a carbon fiber barrel but there is still enough metal in the chamber to set off a metal detector.
There are rumors of a person running a ceramic polymer as a projectile, but nothing has come up anywhere, so it is just rumors. Nothing more.
supposedly, from what I heard it is to keep it cool and together, a la space shuttle due to the heat the firearm can generate.