This should be an interesting project, making your own airsoft anti-tank or anti-materiel rifle. Playing with Weapons does a step-by-step tutorial on how he made one... "This project started of as a cannon to shoot nerf footballs.  I designed it to look like an anti-tank rifle. It can also be used to shoot airsoft bbs."

A vintage Anti-Tank rifle versus the sexy iMac to start our destructive Airsoft Weekend (just imagine the pyros that will be consumed for this gloriously sunny weekend!) from RatedRR... "The Lahti L-39 is a Finnish 20 mm anti-tank rifle used during the Second World War. It had excellent accuracy, penetration and range, but its size made transportation difficult.