Expander Mandrels – 7mm Cartridges

From $50.00

Expander Mandrels are only compatible with SAC Dies.
NOTE: SAC 30 Cal. Dies already include the 5/16″ Collet needed to use the Expander Mandrels. If you need an additional collet they can be purchased separately HERE.
Expander Mandrel Size
NOTE: If you do not currently have a 5/17ER11 Collet installed in your die, you will need to purchase one!
Category: Product ID: 16690


7mm Expander Mandrels

Precision Ground from Solid Carbide.

Available in .0005” Increments

Our solid carbide expander mandrels are made to be used in any of our Modular sizing dies with the appropriate collet.

Required Collet 5/16″

Our Expander Mandrel is unique because it expands the neck of your brass on the “down stroke” instead of the “up stroke” of your press. Furthermore, the precision ground expanding detail is high up in the die, slightly below the cartridge’s neck / shoulder detail. The benefit is that as the cartridge is pulled out of the die, the cartridge neck transitions from the neck bushing to the expander mandrel right away.

  • Ensures a seamless transfer of the cartridge neck from the Neck Sizing Bushing to the Expander Mandrel.
  • Expanding is more consistent because the brass starts off perfectly centered in the die and is immediately expanded as the brass is drawn out of the die body. This is ideal, where expanding on the “up stroke” puts all the stress and pressure on an unsupported case/neck.

All of our Expander Mandrels are rough turned, next they are precision OD Ground for the full length ensuring that all of the outside detail is concentric and ground in the same operation.

In order to pick your mandrel size you will want to understand what the metallurgical properties of your brass are

  • How much spring back the brass currently has if mandreling
  • If unsure here is typically what we see spring back wise with these brass manufacturers.
  • Lapua annealed (.0005″)
  • Lapua unannealed (.001″)
  • All other manufacturers annealed (.001″)
  • All other manufacturers unannealed (.002″)

Again, the above numbers are estimates we have seen with testing internally in the shop.


Additional information

Weight2 oz
Dimensions4 × 3 × 1 in


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