Loading 300 Blk - ep 15 - Subsonic accuracy tests with Hornady A-Max 208gr

Published on March 13, 2016
Duration: 30:50

This video details the process of reloading 300 Blackout subsonic ammunition, focusing on accuracy tests with Hornady A-Max 208gr and Palmetto Projectiles. The instructor demonstrates reloading steps including brass preparation, powder charging with specific loads for Accurate 1680, Reloder 7, and IMR 4198, and bullet seating. The results highlight significant accuracy differences between jacketed and lead bullets, suggesting potential issues with lead bullet diameter for the firearm's twist rate.

Quick Summary

For accurate subsonic 300 Blackout reloads, tested powders include Accurate 1680, Reloder 7, and IMR 4198. Hornady A-Max 208gr jacketed bullets achieved sub-MOA accuracy, while Palmetto Projectiles (0.309 diameter) showed instability, suggesting they may be undersized for the barrel's twist rate.

Chapters

  1. 00:01Introduction to 300 Blackout Subsonic Testing
  2. 00:40Powder Selection for Subsonic Loads
  3. 01:14Reloading Palmetto Projectiles for Accuracy Test
  4. 01:54Reloading Hornady A-Max 208gr for Accuracy Test
  5. 03:24Brass Preparation for Reloading
  6. 06:08Case Length Check and Trimming Decision
  7. 07:48Preparing Cases for Priming
  8. 08:06Flaring Case Mouths for Lead Bullets
  9. 09:28Priming Cases
  10. 10:24Measuring Powder Charges
  11. 11:57Bullet Seating Process
  12. 13:32Setting Dies for Bullet Seating
  13. 19:43Shooting Palmetto Projectiles (No Chronograph)
  14. 20:39Analyzing Palmetto Projectile Bullet Holes
  15. 21:06Shooting Remaining Palmetto Projectiles
  16. 22:49Attaching Chronograph for Jacketed Bullet Test
  17. 23:02Shooting Hornady A-Max 208gr with Chronograph
  18. 24:36Shooting Reloder 7 Loads with Chronograph
  19. 25:24Shooting IMR 4198 Loads with Chronograph
  20. 26:08Conclusions and Analysis of Results
  21. 26:33Investigating Lead Buildup
  22. 27:14Jacketed Bullet Performance Analysis
  23. 28:06Implications for Lead Bullet Diameter
  24. 29:35Final Thoughts and Future Testing

Frequently Asked Questions

What are the recommended powders for 300 Blackout subsonic reloads based on this test?

The instructor found Accurate 1680, Reloder 7, and IMR 4198 to be consistent performers for subsonic 300 Blackout loads that cycle the firearm reliably without a suppressor.

Why did the Palmetto Projectiles show poor accuracy in the 300 Blackout?

The Palmetto Projectiles, at 0.309 diameter, likely exhibited instability due to being undersized for the firearm's barrel twist rate, resulting in oval bullet holes and poor group sizes.

What accuracy was achieved with Hornady A-Max 208gr bullets in 300 Blackout?

The Hornady A-Max 208gr jacketed bullets demonstrated excellent accuracy, achieving a 0.49-inch group with Accurate 1680 powder, which is considered sub-MOA and indicates good barrel stabilization.

How can lead buildup affect shooting accuracy?

Lead buildup in the firearm's chamber and barrel can cause projectiles to become unstable, leading to erratic flight paths, oval bullet holes, and significantly degraded accuracy, as observed in this test.

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