PURPOSE: To promote reliability and long life of an equipment by forming a chemical vapor deposition layer excellent in smoothness with high hardness in furious part of abrasion such as a spiral groove, etc., of a rifle piston.

CONSTITUTION: A chemical vapor deposition layer having three layer construction of a lower layer of TiC, a middle layer of TiC and TiN and an upper layer of TiN is formed in furious part of abrasion such as a spiral groove 2, etc. of a rifle piston 1 of a boring machine used for explosion work, etc., of rocks and concrete. As materials, materials having abrasion and wear resistance such as SNCM 616 (nickel/chromium/molybdic steel), etc., are used. According to the constitution, reliability of an equipment is promoted and, at the same time, long equipment life can be promoted.