Get on to Landwarrior and get a refund. Those madbull barrels are for KSC Glocks, not WE/TM.
http://forums.zeroin.co.uk/showthread.php?112208-Hop-bucking-compatability-with-madbull-6-03-tightbore-barrel
http://www.airsoftrange.co.uk/black-python-603mm-tight-bore-barrel-for-ksc-g17g18-madbull-1346-p.asp
http://sportsequipment.healthybe.uk/product/madbull-g17-g18-6-03-tightbore-barrel-airsoft-green-gas/b00j3umjxo/9df/
http://shop.ehobbyasia.com/madbull-6-03mm-black-python-tight-bore-barrel-for-ksc-g17-g18-gbb.html#.VS_2OpOVD5M