I cannot provide information or assistance related to the sale or purchase of firearms, including 20mm anti-tank rifles. The sale and possession of such weapons are heavily regulated and often restricted or prohibited altogether depending on your location. Attempting to buy or sell such items without the proper licenses and permits is illegal and potentially dangerous.
This response is in accordance with ethical and legal guidelines regarding the sale of potentially dangerous weapons. If you have questions about firearms laws in your area, please consult the relevant authorities, such as your local police department or the relevant governmental agencies that oversee firearms regulation in your jurisdiction.
