308 Win - Lg vs Sm Primers and Flash Holes

Published on July 17, 2019
Duration: 20:32

This guide details an experiment comparing large vs. small primers and flash hole sizes in .308 Winchester cartridges. The expert demonstrates how primer choice and case fill are more critical for ignition reliability than flash hole size, using specific components like Hodgdon H335 and S&B small rifle primers to induce hangfires. The findings highlight systematic variable isolation for precision handloading.

Quick Summary

Expert reloading analysis reveals that primer choice and powder case fill are more critical for ignition reliability in .308 Winchester than flash hole size. Using 'cooler' primers with low case fill powders can induce hangfires, while small primer brass sometimes yields better accuracy. Velocity can decrease with smaller primers.

Chapters

  1. 00:00Introduction: Primer & Flash Hole Experiment
  2. 01:00Experimental Setup: Lapua Brass Types
  3. 02:03Component Selection: Primers & Powder
  4. 03:33Load Data & Baseline Testing
  5. 08:03Range Testing: IMR 4895 Results
  6. 10:11Range Testing: H335 & Ignition Issues
  7. 12:18Analysis: Velocity & Primer Impact
  8. 16:26Conclusion: Critical Factors for Ignition

Frequently Asked Questions

What are the key factors affecting ignition reliability in .308 Winchester reloads?

Primer choice and powder's case fill are more critical than flash hole size. Using 'cooler' primers like S&B small rifle primers with low case fill powders like H335 can lead to hangfires and misfires, even with larger flash holes.

How does primer size affect .308 Winchester velocity?

Switching from large rifle primers to small rifle primers in .308 Winchester loads resulted in an approximate velocity drop of 30-40 feet per second (FPS) in the tested configurations.

Can small primer .308 brass improve accuracy?

In one test using IMR 4895 powder, small primer .308 brass with small flash holes produced significantly better accuracy groups compared to older large primer brass.

What components were used in the .308 Win primer and flash hole experiment?

The experiment utilized Lapua .308 brass (standard LP, Palma SP/SH, modified SP/LH), Sierra 168gr MatchKing bullets, IMR 4895 and Hodgdon H335 powders, and various primers including CCI No. 41, Remington 7 1/2, and S&B small rifle primers.

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