Home made javelin Achievement
Home made javelin20
Destroy an enemy vehicle using the xbow
You will need the HE (explosive) Bolt to complete this. Please reference the "Handyman" achievement for more details. Once you have it, shoot some vehicles. I would advise against tanks, but Littlebirds and any Jeep type vehicle will do nicely. The explosive bolts are not very strong. Hang near a transport vehicle and damage it with a grenade. When someone jumps in, shoot it. Otherwise try and get someone on a quad bike.
An easier way to obtain this achievement rather than destroying vehicles, is by destroying enemy equipment. This DOES count for the achievement.