Lyman M Expander Die

The Lyman M Expander Die improves bullet alignment and case life for reloaders using cast or flat‑base bullets by expanding the case neck from the inside rather than stretching it as a standard expander button does. Its two-step action sets internal neck diameter just under bullet diameter, then finishes the mouth to bullet diameter or slightly over so the bullet starts centered and aligned with the case neck axis.

• Two-step expansion: first step sizes the inside of the case neck to just under bullet diameter for controlled neck tension.
• Finishing step expands the case mouth to bullet diameter or slightly larger, allowing the bullet to be started perfectly centered.
• Reduced case stretching compared with standard expander buttons, extending case life for repeat reloads.
• Adjustable neck plug: setting the plug slightly deeper provides a slight flare of the case mouth useful for cast bullets.

Use the M Expander Die when precise case neck tension, centered bullet start, and reduced neck stretching are priorities for cast or flat‑base bullet reloading. Its design focuses on internal neck expansion and mouth finishing to help produce consistent seating and alignment without relying on external stretching of the case neck.