Cased telescoped ammunition cartridge having a thermal protective insert

A cased telescoped cartridge, comprising:

• a cylindrical case surrounding a projectile, wherein the cylindrical case is made up of a polymer material;
• a front end through which the projectile exits when the cased telescoped cartridge is fired;
• and
• a thermal protective insert located at the front end, wherein the thermal protective insert is made up of a thermally insulating material that is different from the polymer material of the cylindrical case, and wherein the thermal protective insert insulates the cased telescoped cartridge from heat emanating from a barrel of a firearm into a chamber of a firearm when the cased telescoped cartridge is loaded into the chamber of the firearm.