The die is designed to enhance the precision of cast and jacketed bullet reloads by preventing case stretching, a common issue with standard expander buttons. This feature significantly extends the life of the cases. It is an essential tool for users of cast or flat-base bullets. The die operates in two steps: first, it expands the inside of the case neck to just under the bullet diameter, ensuring precise neck tension in the finished reload. The second step involves expanding the case mouth to the bullet diameter or slightly over, allowing the bullet to be perfectly centered and aligned with the case neck axis.