300 Blk - 240gr Sierra Match King subsonics

Published on January 26, 2017
Duration: 32:39

This video details a comprehensive test of the 240gr Sierra Match King bullet for 300 Blackout subsonic applications. The instructor, Johnny, meticulously tests handloads using Accurate 1680 and Hodgdon CFE Black powders in both an 8.5-inch SBR and a 16-inch rifle, both with 1:8 twist barrels. The testing includes initial stabilization checks, velocity measurements, and detailed analysis of group sizes and performance to identify optimal loads for subsonic velocities around 1050 ft/s. The instructor also compares the performance of handloads against factory DT Tactical ammunition.

Quick Summary

Testing of the 240gr Sierra Match King bullet in 300 Blackout confirmed its stability in 1:8 twist barrels. Preferred powders Accurate 1680 and Hodgdon CFE Black were used to develop loads targeting subsonic velocities around 1050 ft/s. The 16-inch rifle achieved excellent accuracy, with groups as tight as 0.8 inches using CFE Black.

Chapters

  1. 00:02Introduction: 300 Blackout Subsonic Series
  2. 00:16Testing the 240gr Sierra Match King Bullet
  3. 00:41Test Firearms: 8.5" SBR & 16" Rifle (1:8 Twist)
  4. 01:04Test Powders: Accurate 1680 & Hodgdon CFE Black
  5. 01:33Factory Ammo: DT Tactical 240gr Match Grade
  6. 03:11Primer Selection: CCI #400
  7. 03:49Initial Function & Stabilization Test
  8. 04:45Accurate 1680 Initial Velocity Test
  9. 05:15CFE Black Initial Velocity Test
  10. 05:43Factory Ammo Initial Test
  11. 06:05Lower Charge Weights Test
  12. 07:26Initial Test Summary & Observations
  13. 08:45Dissecting Factory Ammunition
  14. 11:37Cost Analysis: Sierra Match King Bullets
  15. 12:42Bullet Stability Confirmation
  16. 13:43Preparing for Suppressed Testing
  17. 13:50Velocity Data Analysis & Load Chart Development
  18. 15:57Overall Length Considerations
  19. 16:34Handloading Process: Accurate 1680
  20. 18:27Handloading Process: CFE Black
  21. 19:07Live Fire Testing: 8.5" SBR with Accurate 1680
  22. 20:49Live Fire Testing: 8.5" SBR with CFE Black
  23. 22:11Live Fire Testing: Factory Ammo in 8.5" SBR
  24. 22:49Live Fire Testing: Factory Ammo in 16" Rifle
  25. 23:46Live Fire Testing: 16" Rifle with Accurate 1680
  26. 24:33Live Fire Testing: 16" Rifle with CFE Black
  27. 25:49Final Analysis: Factory Ammo Performance
  28. 27:02Group Analysis: 8.5" SBR Performance
  29. 27:54Chart Analysis: 8.5" SBR Accurate 1680
  30. 28:20Chart Analysis: 8.5" SBR CFE Black
  31. 29:28Analysis: 16" Rifle Performance
  32. 31:11Chart Analysis: 16" Rifle Accurate 1680
  33. 31:35Chart Analysis: 16" Rifle CFE Black
  34. 32:02Conclusion: Outstanding Results & Confidence Boost
  35. 32:33Outro

Frequently Asked Questions

What are the best powders for 300 Blackout subsonic loads with 240gr Sierra Match King bullets?

Based on testing, Accurate 1680 and Hodgdon CFE Black are excellent choices for 300 Blackout subsonic loads using 240gr Sierra Match King bullets. Both powders demonstrated good performance, with CFE Black showing a slight edge in accuracy in some configurations.

Can 1:8 twist barrels stabilize 240gr Sierra Match King bullets in 300 Blackout?

Yes, the testing confirmed that 1:8 twist barrels can effectively stabilize the 240gr Sierra Match King bullet in 300 Blackout, even at subsonic velocities around 1050 ft/s, which was a point of concern for the instructor.

What are optimal subsonic velocities for 300 Blackout with 240gr bullets?

The target subsonic velocity for 300 Blackout with 240gr bullets in this test was approximately 1050 ft/s. Loads were developed to achieve this, with final charges of 11.7 grains of Accurate 1680 and 11.9 grains of CFE Black in a 16-inch barrel averaging around 1050 ft/s.

How does factory DT Tactical 240gr 300 Blackout ammo perform compared to handloads?

Factory DT Tactical 240gr ammunition showed mixed results. While it performed well in a 16-inch rifle, achieving a 1.1-inch group, it was less consistent in an 8.5-inch SBR. Handloads with Accurate 1680 and CFE Black generally offered more predictable and tighter groups.

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