G&G precision barrel 6.03mm 357mm

Precision barrels are best described as an inner barrel with a diameter of 6.04mm or less. Precision inner barrels allow for better compression, improved accuracy, and in a few cases increase muzzle velocity. Although precision barrels often require more maintenance and cleaning, they can give an AEG a greater range and improve the overall performance of an airsoft AEG.

G&G 6.03mm barrels are nickel plated high quality aluminium. 

Remember when upgrading into tight bore inner barrel that you also need to upgrade your BBs to match the barrels requirements.