Changing the barrel on an Airsoft rifle to make it longer or tighter will improve accuracy. Poor quality BBs will jam in a tight barrel, however. Most automatic electric guns (AEG) come with a default stock of 6.08 mm diameter. Barrels come as tight as 6.01 mm to 6.05 mm. Some manufacturers make a 6.04 mm barrel with a special coating, which increases the feet per second (FPS) by up to 10 times, or more.
1. Remove the gun’s BB magazine. Fire the gun three times in semi-auto mode to make sure there are no BBs in the chamber. Remove the battery from the gun.
2. Remove the back pin from the receiver.
3. Remove the front pin and split the lower receiver from the upper receiver. Pull the receiver apart (this will require force). Do not break the tabs.
4. Pull out the barrel and remove the four screws from the outer barrel and receiver assembly.
5. Separate the outer barrel from the receiver.
6. Slide out the inner barrel.
7. Remove the clip with needlenose pliers from the hop-up unit.
8. Slide the barrel out of the hop-up unit carefully.
9. Slide the bucking off the barrel; now affix the new barrel.
10. Reversing the steps to reassemble the rifle with its new barrel.