RE: 1/6 scale stuart
The "short" barrel is to launch the stupid kids like missile. It must be replaced. Also, if you are to regularly run your Stuart, you must take the precaution of reinforcing the front sprockets with a small hose clamp where the axle slides into the back side. In time, the plastic WILL fail and break off. It can be reglued and clamped but it just saves that from happening.