.308 Win - 175gr Sierra Match King with IMR 4064 (part 2)

Published on June 11, 2018
Duration: 29:16

This video details a reloading project for .308 Win using 175gr Sierra Match King bullets and IMR 4064 powder, aiming to replicate Federal Gold Medal Match performance. Testing involved a load ladder from 42.0 to 42.8 grains in a JP Supermatch barrel, with both suppressed and unsuppressed firing. Case capacity differences between brass types were highlighted as a critical factor for pressure management, especially with military brass. While accuracy was generally disappointing, the best group achieved was 0.902 inches unsuppressed at 42.4 grains.

Quick Summary

This .308 Win reloading test aimed to match Federal Gold Medal Match performance using 175gr Sierra Match King bullets and IMR 4064 powder. Testing revealed significant case capacity differences between brass types, impacting pressure. The best accuracy achieved was 0.902 inches unsuppressed at 42.4 grains.

Chapters

  1. 00:00Project Overview & Goal
  2. 01:27Brass Case Capacity Comparison
  3. 06:45Chamber Dimensions & Resizing
  4. 12:01Suppressed Range Testing
  5. 18:26Unsuppressed Range Testing
  6. 22:41Brass Inspection & Pressure Signs
  7. 24:39Conclusion & Future Testing

Frequently Asked Questions

What was the goal of this .308 Win reloading test?

The primary goal was to replicate the performance of Federal Gold Medal Match ammunition using IMR 4064 powder and 175gr Sierra Match King bullets in a .308 Winchester caliber.

How did different brass types affect case capacity in the .308 Win test?

Lapua brass had the highest capacity (56.0gr), while IMI had the lowest (53.4gr). This significant difference means using military brass like IMI with loads developed for Lapua can cause dangerous pressure increases.

What were the accuracy results for the 175gr Sierra Match King loads?

Accuracy was generally disappointing. The best group achieved was 0.902 inches at 100 yards with 42.4 grains of IMR 4064, fired unsuppressed. Most groups were larger.

What caused ejector marks and brass burrs when shooting suppressed?

The speaker suggests that ejector marks and brass burrs observed on all loads when suppressed are likely due to the mechanical timing of the AR-10 platform, not necessarily over-pressure, as primers remained rounded.

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