300 Blk Sizing Die Shootout - Part 2

Published on September 13, 2017
Duration: 26:50

This video details a comprehensive shootout of 300 Blackout sizing dies, focusing on brass forming and neck tension. The instructor analyzes various brass headstamps, comparing the performance of Lee, Forster, and RCBS dies. Key findings include identifying problematic brass (PPU, Wolf) due to neck thickness and demonstrating methods to measure and improve neck tension, such as modifying expander balls and adjusting headspace. The analysis emphasizes the critical role of proper sizing for reliable chambering and preventing bullet setback.

Quick Summary

When forming 300 Blackout brass, neck thickness and neck tension are paramount. Excessive neck thickness prevents chambering, while insufficient neck tension can lead to dangerous bullet setback. Dies like Forster and RCBS generally offer better performance, though modifications to Lee dies may be necessary to achieve adequate neck tension and prevent bullet movement.

Chapters

  1. 00:00Introduction to 300 Blackout Sizing Dies
  2. 00:20Recap of Dies and Brass Tested
  3. 01:01Critical Factor: Neck Thickness
  4. 02:45PPU and Wolf Brass Issues with Lee Die
  5. 03:58RCBS and Forster Die Performance
  6. 04:54Neck Tension Insights and Resources
  7. 06:47Measuring Neck Diameter Change After Bullet Seating
  8. 07:54Neck Diameter Growth with Forster/RCBS Dies
  9. 08:23The 'Slam Chart' and Neck Tension Verification
  10. 09:55Mushy Chambering and Lee Die Issues
  11. 11:03Lee Die's Intended Use vs. Forming
  12. 11:55Accuracy Data Limitations
  13. 13:41Powder Performance and Velocity Observations
  14. 14:43Shell Holder Impact on Headspace
  15. 17:40Future Modifications and Testing Plans
  16. 18:08Forster Honed Die Concept
  17. 19:47Measuring Sized Neck Diameter Without Expander
  18. 22:39Gem-Tech Brass Issues and Round Stretch
  19. 24:43Summary and Next Steps
  20. 26:31Conclusion and Support

Frequently Asked Questions

What are the critical factors when forming 300 Blackout brass?

The most critical factors when forming 300 Blackout brass are neck thickness and ensuring proper neck tension. Excessive neck thickness can prevent chambering, while insufficient neck tension can lead to bullet setback, affecting pressure and safety. Consistent headspace is also vital for reliable function.

Which 300 Blackout sizing dies performed best in the test?

The Forster and RCBS 300 Blackout sizing dies generally performed better than the Lee die. The Lee die's expander ball was found to be too large, resulting in insufficient neck tension and bullet setback. Modifications to the Lee die's expander ball were suggested to improve its performance.

How can neck tension be improved for 300 Blackout reloads?

Neck tension can be improved by using resizing dies that provide adequate neck sizing, such as Forster or RCBS. If using a die like the Lee, modifying the expander ball by sanding it down can increase neck tension. Ensuring the brass neck thickness is within acceptable limits is also crucial.

What is bullet setback and why is it a concern in 300 Blackout?

Bullet setback occurs when the bullet is pushed deeper into the case during chambering. In 300 Blackout, this reduces case volume, increasing internal pressure, which can be dangerous. It's often caused by insufficient neck tension, allowing the bullet to move easily.

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