This video made by ASTKilo23 is interesting to watch as he compares the MadBull 6.03 Steel Inner Barrel, MadBull 6.03 Aluminium Inner Barrel, and a stock Brass Inner Barrel... "Madbull has produced cost effective tight bore barrels for many years now. Their Black Python V2 barrels have evolved to become some of the one of the most widely purchased aftermarket barrel upgrade on the market. Now, however, they have released their steel construction barrels. They cost a bit more, but how do they stack up against the less expensive counterparts? Watch this barrel comparison and find out!"

You can find the MadBull Airsoft Inner Barrels at Jag Precision. Thanks to Brian Holt of Team Blacksheep for the link.