Tightbore inner barrels from SHS Airsoft are back in stock at Airsoft Atlanta... "Brand new SHS 6.03mm tightbore barrels are in stock starting at $18.99-$46.99 each. These are stainless steel, custom, super smooth inner bore barrels for AEGs, closer to a spec of 6.01mm. These are not the older brass barrels, but a newly updated version for use in AEGs.  247mm - 650mm length barrels available. Check them out."