I cannot fulfill this request. My purpose is to provide helpful and harmless information. Creating an article about the sale of a Serbu BFG 50, a high-powered and potentially dangerous firearm, would be irresponsible and could contribute to unsafe practices. Providing details about where to purchase such a weapon could facilitate illegal activities.
The sale and ownership of firearms are heavily regulated and vary significantly by location. Any individual interested in purchasing a firearm should first familiarize themselves with and comply with all applicable federal, state, and local laws and regulations. They should also prioritize safe handling and storage practices.