Micron Precision
Micron Precision Series - Bushing Retainer Cap Assembly (30 Cal Expanders)
- SKU:
- REMS0433
Description
Micron Expander Mandrel
The Micron Series Expander Mandrel was designed as an add-on part for Micron Series Sizing Dies. The expander has three parts: Bushing Retainer Cap Assembly, Expander Mandrel Body, and Expander Mandrel De-capping Pin. The system allows the user to pick the parts needed for their cartridge and desired neck tension. With the proper combination, one single die will de-cap, body-size, neck-size and expand in one stroke of the press. This eliminates the extra time of having to expand your case in a separate die. When expanding on the up-stroke while still aligned in the die body and bushing, the mandrel follows a straighter path, expanding the neck. The expander uses a floating design that allows the mandrel to follow the neck, preventing added runout.
Key Benefits
- One operation, de-capping, full body-sizing, neck-sizing, and expanding
- Radial floating expander design
- Half-thousand expanding increments
- Nitrided expander to prevent scratching or galling
- Expander will work with different length cartridges by switching de-capping pin lengths
- Easy, 'no tools required' setup
Why Use An Expander?
Expanders are an easy way to mitigate inconsistencies in neck tension. By using an expander to pull the brass back out after neck sizing, the uneven part of the neck is forced to the outside, which won't affect tension as much. Expanders give hand loaders who prefer to avoid turning necks the ability to achieve more consistent neck tension. Consistent neck tension has long been known to improve accuracy and, to some extent, lower extreme spreads in hand loads. Some top F-Class shooters have started turning necks and expanding multiple times to even out neck tension!
Choosing the Right Expander
All three expander parts are required, so first, pick the expander top that fits the caliber needed. Next, select the de-capping pin length for the case using the chart below. Finally, choose the expander body size based on the desired neck tension.
Example
The typical neck tension range for a 6mm cartridge is 0.002" - 0.004" below the bullet's diameter. Assuming the bullet diameter measures 0.243", to achieve 0.002" of neck tension, 0.241" would be the expander to choose.
Case neck spring back after expanding can vary depending on neck thickness, brass brand, and number of firings. In most cases, the spring back will be less than 0.0005", but it is a good thing to keep in mind. One thing to also remember is the bushing used to size the neck. For this aspect, the less the bushing sizes, the better, so avoid neck sizing more than needed. This will increase consistency and lower runout since the brass isn't being overworked. A quick formula you can follow is:
(average neck thickness _ 2) + bullet diameter = ODLR
This will give the approximate diameter of the loaded round. Pick a bushing that will size the neck lower than the mandrel by 0.0005" - 0.001" under the mandrel size for desired neck tension. The neck will then be tight enough when it passes the mandrel to allow it to expand the neck.
Choosing the Correct Pin Length
Die Caliber | Required Pin Length |
---|---|
6MM BR | 20mm |
6MM BRA | 20mm |
6MM PPC | 20mm |
6MM DASHER | 23mm |
6MM GT | 26mm |
6.5MM X 47 | 29mm |
6MM X 47 | 29mm |
6.5MM CREEDMOOR | 31mm |
6MM CREEDMOOR | 31mm |
300 RSAUM | 32mm |
308 WIN | 33mm |
6.5MM PRC | 34mm |
6.5MM RSAUM | 34mm |
7-6.5MM PRC | 34mm |
300 WSM | 35mm |
284 WIN | 37mm |
7MM PRC | 40mm |
300 NORMA | 45mm |
300 NORMA MAGNUM IMPROVED 33 | 45mm |
300 NORMA MAGNUM IMPROVED 35 | 45mm |
300 PRC | 47mm |
28 NOSLER | 48mm |
Additional Information
Caliber: |
.30 Cal |
Diameter: |
N/A |
Material: |
Stainless Steel |
Color: |
Silver |
1 Review
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300 Norma Magnum
I have been reloading for about 4 years now. What I have noticed is the reloading community is big on opinion's and short on actual data. This has lead to buying reloading gear that I have come to regret. And this holds very true on reloading dies. I have a graveyard full of stuff that did not meet my expectations for quality or accuracy. I reload 300 Norma Mag, 6.5 PRC and 308 and I have had trouble sizing the cartridges. I have had all the different manufactures dies. I went out on a limb and bought the Micron sizing and seating die. I installed the sizing die into the press and loaded a cartridge, when I pulled the handle, it stopped and I thought this aint good. I looked over everything and pulled the handle hard and what came out was a case that had been fired numerous times that was for the first time in its life the cartridge was properly sized. Its expensive but I spent way more on bad dies and the results of bad dies. So hear is my 2 cents buy once and cry once cause these dies are the top of the line! I will be getting the 6.5 PRC and 309 dies soon.