21st Century Caliber Specific Expander Mandrels are now available in Black Nitride!  Black Nitride adds a degree of hardness and friction reduction to the surface of the mandrel.  This helps minimize galling that can occur.  

Our Black Nitride Caliber Specific Expander Mandrels are available in .0005” increments in calibers 22 to 338.  Incremental mandrels will allow the reloader to find proper neck tension to fine-tune their loads. We recommend our Moly Dry Neck Lube for use with all of our expander mandrels Moly Dry Neck Lube (21stcenturyinnovation.com).

Looking for a complete kit?  Save money and get a kit here:  Black Nitride Caliber Specific Expander Mandrel Kits

Expander Die Bodies sold separately. 

21st Century Expander Mandrels and Arbors are designed for proper fit in our die bodies. While these may work in most Sinclair and PMA die bodies we cannot guarantee proper fitment in those bodies.

Machined to hold a tolerance of  +/_  .0002"

*PLEASE USE MICROMETERS TO MEASURE