Sadlak M14 TiN coated NM gas piston.   Sadlak precision pistons are made to the exact GI specifications with all critical dimensions individually inspected. The 420 stainless material and heat-treating operations are both certified to assure quality. The pistons have a highly polished surfaced using a non-contact electro-polishing method that maintains tolerance on the critical diameter and does not “round–over” the edges on the grooves. The pistons are then hard coated with a gold colored Titanium Nitride (TiN) finish. This coating, often used on machine cutting tools, helps reduce galling and pitting and holds up better to the high heat and abrasiveness of gunpowder and primers. The resulting effect is a smoother action and an improved life of the piston and cylinder.