RE: My ultimate HL airsoft upgrade
ebay. I like the Systema brass barrels, they are 6.04mm diameter. The MadBulls are aluminum, I didn't have any luck with it, but I gave it to a fellow tanker and he said it rocked! The MadBulls are 6.03mm. If using the brass barrel, you'll want to add counter weights at the rear and sides of your turret, it's heavy.