What type of bullet is characterized by the explosive charge being located around the junction of the jacket and base?

The type of bullet characterized by the explosive charge being located around the junction of the jacket and base is known as a core fire primer. In this type of ammunition, the primer is designed to ignite the powder charge when struck, providing an efficient and reliable ignition system. The distinctive feature of the core fire primer is its placement at this junction, which contributes to the overall function of the bullet by ensuring that the explosive charge is well-placed for effective firing.

Understanding this design is crucial for those studying ammunition components and their operation. In contrast, other primer types serve different mechanisms or functions that do not align with the specific description provided in the question. For instance, a rim fire primer contains the explosive compound on the rim of the cartridge, which differs fundamentally from the core fire primer's construction. This highlights the unique characteristics and engineering involved in various types of ammunition.