Expanding mandrel dies

From $65.00

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21 in stock (can be backordered)



Mandrel dies

The expander mandrel die holds the expander mandrels which.  Our expander mandrel dies are compatible with 21st Century expander mandrels.  You can buy our expander mandrels here:  https://www.shootsmallgroups.com/product/mandrels/

Our dies are coated with Black nitride and are cartridge family specific.  What it means is that a 6BR will work with 6BR, Dasher, BRX, BRA, etc.  A 284 die will work with 284 Winchester, 284 Shehane, and any other variants of the 284 case.

Our expander mandrel dies size the base of the case the same way your Full Length sizing die would.  This helps align the case with the mandrel and also helps reduce “clickers” as brass ages.

How to set up our expander mandrel dies.

  1. Run press all the way up.
  2. Thread die onto press until the die touches the shell holder.
  3. Lock die down in position.
  4. Done.

Note:  You could also use the 6BR die in a 308 Winchester or any other cartridge with same case base diameter.  You would simply have to back the die off so that the case mouth does not bottom on on the mandrel. 

Expander Mandrels

Our expander mandrels are available in 0.0005″ increments.

The purpose of the expander mandrel is to ensure a precise and consistent inner diameter of the case neck. This is crucial because it directly affects the bullet’s fit and alignment with the barrel of the firearm. A proper fit and alignment contribute to accuracy and consistency in shooting.

During the reloading process, the case is placed on the expander mandrel, and the reloading press is activated. As the press exerts downward force, the mandrel expands the case neck by gently pushing against its inner walls. This expansion process is controlled and precise, ensuring that the case neck maintains a uniform and consistent inner diameter.

After expansion with expander mandrel, and the case can then be filled with powder and fitted with a bullet. The expanded case neck allows for easy bullet insertion and ensures a secure grip on the bullet without excessive tension or looseness.

By using an expander mandrel, precision ammunition reloaders can achieve consistent and reliable results in terms of bullet seating depth, bullet release, and overall shooting performance.

Our expander mandrels are compatible with 21st Century expander mandrel dies.  Our expander mandrels are made of 300 Series Stainless Steel and coated with Armoloy.

The benefits of Armoloy coating include:

  1. Wear Resistance: The Armoloy coating significantly increases the surface hardness of the treated parts, improving their resistance to wear, abrasion, and friction. This helps extend the service life of the components and reduces the need for frequent replacements.
  2. Low Friction: The smooth and lubricious nature of the Armoloy coating reduces friction between moving parts, resulting in smoother operation, reduced heat generation, and improved overall efficiency.
  3. Chemical Resistance: Armoloy-coated surfaces are resistant to various chemicals, solvents, and cleaning agents.

Try our expander mandrel dies.  Our dies are cartridge family specific and size the base of the case as you expand the necks.  https://www.shootsmallgroups.com/product/expanding-mandrel-dies/

Brush Cap

This cap fits our mandrel dies as well as 21st Century mandrel dies.  You can install the brush and it will allow you to brush the inside of your necks using a press rather than doing it by hand.

If you have a progressive press, you can add this brush to one or even two of the stations to brush your necks as you process the brass.

If you are using mandrel dies other than ours, run the press all the way up and make sure brush is about 1/4 inch off the shellholder so that it does not bottom out when the ram comes up.

*Brush not included.

Additional information


6 BR/6GT, .284 Winchester, 6.5 PRC/7mm PRCW, .308 Win/Creedmoor/6.5×47 Lapua/XC, WSM, RSAUM