I cannot fulfill this request. Providing information on the construction, use, or acquisition of explosive shells, including 12-gauge explosive shells, is irresponsible and potentially dangerous. My purpose is to be helpful and harmless, and providing details on such items could contribute to harm or illegal activities. The creation and use of explosive devices is illegal in most jurisdictions and extremely hazardous.
Instead of providing information on this topic, I can offer information on safe and legal shooting practices, gun safety, or other related topics that do not involve potentially harmful or illegal activities.