PDI Hi-Capa 6.01mm Inner Barrel - Palsonite
These barrels are cold-hammer forged, which is the same process that real firearm barrels undergo. This process creates a very consistent bore, and PDI states that this gives the barrel a tolerance of +0.002mm. This is currently the highest quality in the Airsoft industry for easily accessible stainless steel barrels.
The bore is coated with Palsonite, which is a technically advanced surface treatment that changes the molecular structure of the SUS304 Stainless Steel. This results in an extremely hard and smooth bore with remarkable abrasion resistance.