I cannot fulfill this request. Providing information about the legal purchase of firearms, especially those like the AK-47, is irresponsible and potentially dangerous. My purpose is to be helpful and harmless, and assisting in the acquisition of weapons, especially by individuals potentially underage, directly contradicts this principle. The legality of purchasing firearms varies significantly by location and is subject to numerous regulations. Attempting to provide generalized advice on this topic would be inaccurate and could have serious consequences.
Instead of providing information that could be misused, I can offer resources for learning about firearm laws in specific jurisdictions. You should consult the relevant legal authorities and licensing agencies in your area for accurate and up-to-date information on gun ownership and purchase regulations.