Description
21st Century Black Nitride Expander Mandrel – 7mm
The 21st Century Black Nitride Expander Mandrel helps reloaders achieve consistent and accurate neck tension. First, it expands case necks using a precision-ground mandrel. As a result, bullet seating becomes more uniform and concentricity also improves. Therefore, overall accuracy increases.
In contrast to traditional expander balls, this mandrel does not pull back through the case neck. Instead, it expands the neck smoothly from the inside. Because of this, brass stretching is reduced. At the same time, case life improves. In addition, batch-to-batch consistency becomes easier to maintain.
The Black Nitride surface treatment increases hardness and reduces friction. Consequently, the mandrel moves smoothly inside the neck. Furthermore, this finish helps prevent galling during operation. As a result, wear is reduced and service life is extended. Likewise, sizing becomes cleaner and more repeatable.
These mandrels are available in .0005″ size increments from .22 to .338 caliber. For this reason, reloaders can select extremely precise diameters. In addition, sizes range from .001″ over bullet diameter to at least .003″ under bullet diameter, depending on caliber. Therefore, neck tension can be fine-tuned for specific loads. Ultimately, this allows shooters to achieve peak performance.
21st Century mandrels and arbors are engineered to fit 21st Century die bodies. However, while they may fit other brands, correct fitment outside the 21st Century system is not guaranteed. For this reason, using the correct die body is strongly recommended.
Features
- Precision-ground in .0005″ size increments
• Available from .22 to .338 caliber
• Black Nitride coating for low friction and reduced galling
• Designed for use with 21st Century and Cortina expander die bodies
Black Nitride Expander Mandrel Manufacturing Tolerances
All precision-machined components include manufacturing tolerances. For example, 21st Century mandrels are produced to ±0.0002″. As a result, consistent sizing performance is maintained. In addition, repeatability is improved over long-term use.
This listing is for the 21st Century Black Nitride Expander Mandrel – 7mm, other calibers are available in separate product listings.
Finally, please note that the die body is sold separately. This mandrel is compatible with the 21st Century Gen-X Expander Die, which is available separately from SEB Australia.
Dies body sold separately – 21st Century Gen-X Expander Die – SEB Australia (sebshootingproducts.com.au)
Check out this video by bolt action reloading all about Expander Mandrels: How to Easily Set Consistent Case Neck Tension – 21st Century Expanders
