The .308 Winchester, a stalwart of the hunting and long-range shooting world, isn't typically associated with subsonic ammunition. However, for specific applications like suppressed shooting or close-range hunting where a lack of supersonic crack is crucial, subsonic .308 loads offer a distinct advantage. This guide delves into the intricacies of loading subsonic .308 Winchester ammunition, exploring its benefits, challenges, and considerations.
Understanding Subsonic Ammunition
Subsonic ammunition, by definition, travels slower than the speed of sound (approximately 1125 feet per second or 343 meters per second). This slower velocity significantly reduces the characteristic "crack" of a supersonic bullet breaking the sound barrier, resulting in a quieter shot. This is particularly advantageous for hunting in noise-sensitive areas or when using a suppressor.
Benefits of Subsonic .308 Winchester Loads
- Reduced Noise: The primary benefit is the significant reduction in noise, making it ideal for hunting where sound disruption is undesirable or when operating with a suppressor.
- Improved Accuracy with Suppressors: Subsonic loads often exhibit better accuracy when fired through a suppressor, as the bullet's stability isn't compromised by the shockwave of breaking the sound barrier.
- Specialized Applications: Subsonic .308 might be preferred in close-quarters scenarios where overpenetration is a concern, although bullet selection remains crucial here.
Challenges of Subsonic .308 Winchester Loads
- Reduced Range and Energy: The lower velocity inherently results in a shorter effective range and reduced stopping power compared to supersonic loads. This significantly limits its use for long-range hunting.
- Increased Sensitivity to Barrel Length: Subsonic loads can be more sensitive to barrel length than supersonic rounds. An improperly tuned barrel length might hinder performance and accuracy.
- Potential for Unreliable Functioning: Heavier bullets and slower velocities can sometimes lead to malfunctions in semi-automatic rifles due to insufficient recoil impulse to cycle the action reliably. Careful load development is essential.
- Finding Reliable Components: Sourcing suitable components for subsonic loads, such as heavy bullets and appropriate powders, might require more research and effort.
Components and Load Development for Subsonic .308 Winchester
Crafting reliable subsonic .308 loads necessitates careful consideration of the following:
1. Bullets:
Heavier bullets (typically 180 grains or more) are essential for achieving subsonic velocities while maintaining sufficient stability. Lead core, jacketed lead, and full metal jacket (FMJ) bullets are all viable options.
2. Powders:
Slow-burning powders are necessary to generate sufficient pressure for reliable ignition and cycling while keeping velocities subsonic. Specific powder recommendations will vary greatly depending on the chosen bullet weight and your rifle's characteristics. Consult reloading manuals for suitable powder options.
3. Cases:
Standard .308 Winchester cases are suitable. Ensure they are properly sized and prepared before loading.
4. Primers:
Standard rifle primers are generally sufficient.
Load Development Process:
Disclaimer: Reloading ammunition is inherently dangerous. Improperly loaded ammunition can result in serious injury or death. Always consult reliable reloading manuals, prioritize safety, and start with minimal powder charges. Gradually increase powder charges while meticulously recording your results. This information is for educational purposes only and does not constitute advice to reload ammunition.
- Start with published data: Begin with loading data from a reputable reloading manual, choosing a starting load specifically designed for subsonic velocities.
- Accurate measurements: Precisely measure all components using a scale and other appropriate tools.
- Gradual increases: Incrementally increase powder charges, carefully recording velocity and pressure measurements at each step using a chronograph.
- Observe for pressure signs: Watch closely for any signs of excessive pressure, such as flattened primers or unusually high chamber pressure.
- Functionality test: Check for reliable cycling in your firearm.
- Accuracy testing: Finally, evaluate accuracy at various ranges.
Conclusion:
Subsonic .308 Winchester loads offer unique advantages in specific situations, but they also present challenges. Successful subsonic load development requires patience, precision, and a thorough understanding of reloading principles. Prioritize safety above all else, and consult reliable resources and reloading manuals before attempting to load your own ammunition. Always remember that responsible gun ownership includes a thorough understanding of your firearm and ammunition.
