The cavity in the PTM is a bead blasted finish. It is possible that the cavity was coated with a paint, but I really don’t know for sure. The wear we have seen is usually just a dulling out of the bead blast. As far as the material, it is 8620 carbon steel, which has similar properties to the 1035 carbon steel the TE’s are made from. The 8620 is used on the PTM because it is better to use on form forged designs. The TE is billet forged. Two different processes used in the manufacture of the two designs.