ESTES Bull Pup 12D Model Rocket KitEST7000 Bull Pup 12D Model Rocket Kit, Skill Level 2 The Estes Bull Pup 12D is a highly detailed version of the USAF AGM 12D Bull Pup air to ground missile. First developed in the 1950s, the Bull Pup was used in combat until the 1970s. Over 30,000 Bull Pups were built and used until it was decommissioned in the mid 80s. If you're just getting started in scale model rockets, the Bull Pup 12D is a great kit to develop your scale model building skills.