The M855A1, The Whole Truth

Published on October 26, 2024
Duration: 22:39

The M855A1 cartridge significantly increases chamber pressure (59,160 PSI vs. 51,522 PSI for M855) to achieve M4A1 carbine velocities, leading to accelerated barrel wear and reduced service life. It requires specialized magazines like the EPM or PMAG Gen 3 due to its projectile design and feeding characteristics. While offering improved penetration over M855, its overall effectiveness is debated due to these drawbacks.

Quick Summary

The M855A1 ammunition increases chamber pressure to approximately 59,160 PSI, significantly higher than the M855's 51,522 PSI. This, combined with its copper projectile, drastically reduces barrel life and necessitates specialized magazines like the EPM for reliable feeding and to prevent damage.

Chapters

  1. 00:00Introduction: M855A1 Follow-Up
  2. 01:07Evolution of 5.56mm Cartridges
  3. 02:05Projectile Composition and Stability
  4. 03:41Pressure and Carbine Performance
  5. 05:16Barrel Wear and PSI Comparisons
  6. 06:38Feeding Issues and Magazine Solutions
  7. 08:58NATO Standardization and Velocity Data
  8. 11:53Propellant Additives Explained
  9. 14:20Penetration and Terminal Performance Tests
  10. 16:49Accuracy and Zeroing Considerations
  11. 18:55Conclusion: Program Assessment

Frequently Asked Questions

What are the main drawbacks of the M855A1 ammunition?

The M855A1 significantly increases chamber pressure, leading to accelerated barrel wear and reduced weapon longevity. It also requires specialized magazines like the EPM due to its projectile design, and it is not NATO standardized, causing interoperability issues.

How does the M855A1 affect firearm barrel life?

The M855A1 operates at higher pressures (around 59,160 PSI) and uses a harder copper projectile. This combination effectively halves the service life of a firearm barrel compared to older ammunition like the M855.

Why are special magazines needed for the M855A1?

The exposed steel penetrator tip on the M855A1 projectile can cause damage to standard barrel extensions and upper receivers. Specialized magazines, such as the Enhanced Performance Magazine (EPM), improve feeding angles and mitigate these issues.

Does the M855A1 offer improved penetration capabilities?

Yes, testing shows the M855A1 has superior penetration against 1/2-inch steel plates compared to the older M855 round. However, it is still outperformed in penetration by dedicated armor-piercing rounds like the M995 AP.

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