PDI barrels are cold-hammer forged from stainless steel, which is the same process how real rifle barrels are produced. They have a superior tolerance and roundness of the inner surface compared to anything else on the market.

PDI 01 6.01mm Precision Inner Barrel for Western Arms M9A1 Series GBB
Stainless steel Construction
Internal diameter 6.01mm built for precision shooting
8mm Outer Diameter
Advance Technology forming by Cold Forging on Stainless Steel result in tolerance no more than
Suitable for Western Arms WA M9A1 Series Airsoft Gas Blow Back GBB Pistol

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