308 Win - Lg vs Sm Primers and Flash Holes

Published on July 17, 2019
Duration: 20:32

This experiment investigates the impact of primer size and flash hole diameter on ignition reliability in .308 Winchester. Using Lapua brass with different primer and flash hole configurations, the test revealed that 'cooler' Sellier & Bellot small rifle primers combined with Hodgdon H335 powder and low case fill reliably induced hangfires, especially with small flash holes. Conversely, IMR 4895 showed consistent ignition across all setups, with small primer brass even yielding better accuracy.

Quick Summary

Primer choice and case fill are more critical for reliable ignition in .308 Winchester reloads than flash hole size. 'Cooler' primers like Sellier & Bellot combined with low case fill and powders like H335 can cause hangfires, even with small flash holes.

Chapters

  1. 00:00Intro: Primer & Flash Hole Test .308 Win
  2. 01:00Experimental Setup: Lapua Brass Types
  3. 02:03Component Selection: Primers & Powder
  4. 03:33Load Data & Baseline: 168gr SMK
  5. 08:03Range Test: IMR 4895 Results
  6. 10:11Range Test: H335 Ignition Issues
  7. 12:18Analysis: Velocity & Ignition Factors
  8. 16:26Conclusion: Primer & Case Fill Criticality

Frequently Asked Questions

What factors are most critical for reliable ignition in .308 Winchester reloads?

According to Johnny's Reloading Bench, primer choice and case fill are more critical for reliable ignition than flash hole size. Using 'cooler' primers with low case fill and certain powders can induce ignition problems.

Does small primer brass improve accuracy in .308 Winchester?

In this specific test using IMR 4895, the small primer brass configurations for .308 Winchester actually produced significantly better accuracy groups compared to the large primer brass.

Can small flash holes prevent hangfires in .308 Win reloads?

No, the experiment showed that small flash holes did not prevent hangfires when using a combination of 'cooler' small rifle primers, low case fill, and Hodgdon H335 powder in .308 Winchester.

How does primer size affect velocity in .308 Winchester?

Switching from large rifle primers to small rifle primers in .308 Winchester resulted in a noticeable velocity drop, approximately 30-40 feet per second, according to the test data.

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