I've heard this before -I am motorcyclist and used to do some club level racing, I always wondered why TiN or DLC found on high end fork tubes was not used in AR/M4 BCG's. An amorer buddy of mine opined on the balance of anti corrosive properties, the ability to maintain lubriciation/slickness and durability limited the range of coatings to few options. In his mind, phosphate coating is still the standard.

