The .45-70 Government cartridge, a venerable round with a rich history, is experiencing a resurgence in popularity. While traditionally known for its powerful hunting capabilities, many shooters are discovering its potential for subsonic applications. This article will delve into the intricacies of subsonic .45-70 Gov't load data, providing a comprehensive guide for safe and effective reloading. We'll cover various powder choices, bullet weights, and the crucial considerations for achieving consistent subsonic performance. Understanding subsonic 45-70 load data is key to unlocking this cartridge's versatility for both target shooting and quieter hunting scenarios.
Understanding Subsonic Velocity
Before diving into specific load data, it's crucial to understand what constitutes "subsonic." Subsonic velocity refers to a projectile speed slower than the speed of sound, generally around 1125 feet per second (fps) at sea level. Achieving subsonic velocities with the .45-70 requires careful selection of powder and bullet weight. Going subsonic offers several advantages: reduced noise, minimized recoil, and often improved accuracy at shorter ranges.
Factors Affecting Subsonic Velocity
Several factors influence the velocity of a subsonic .45-70 load:
-
Powder Type: Certain powders burn more slowly and produce less pressure, making them ideal for subsonic loads. Examples include Trail Boss, Unique, and IMR 4759. Each powder has its own burn rate, influencing the pressure curve and velocity. Careful experimentation and adherence to published data are essential.
-
Bullet Weight: Heavier bullets naturally achieve lower velocities at a given powder charge compared to lighter ones. Bullets in the 400-500 grain range are commonly used for subsonic .45-70 loads. The increased mass helps to maintain energy and accuracy at lower speeds.
-
Barrel Length: A longer barrel allows for more complete powder burn, potentially increasing velocity beyond the desired subsonic range. Shorter barrels are generally preferred for subsonic loads to ensure the round stays below the sound barrier.
-
Altitude and Temperature: Environmental factors like altitude and temperature affect air density, influencing bullet velocity. Higher altitudes and colder temperatures reduce air density, resulting in slightly higher velocities.
Choosing the Right Components
Selecting appropriate components is paramount for achieving reliable and safe subsonic .45-70 loads.
Powders for Subsonic Loads
Several powders are well-suited for subsonic .45-70 loads:
-
Trail Boss: This unique powder is specifically designed for low-pressure loads and is a popular choice for subsonic applications. Its volumetric charge facilitates consistent metering and ease of loading.
-
Unique: A versatile powder that can provide reliable subsonic performance in the .45-70, although it might need more careful attention to charge weight than Trail Boss.
-
IMR 4759: Another slower-burning powder suitable for subsonic loads, offering a balance of accuracy and low pressure.
Note: Always consult published load data from reputable sources before attempting any reloading. Never exceed the maximum listed charge.
Bullet Selection
Heavier bullets are preferred for subsonic loads to maintain sufficient energy at lower velocities. Common choices include:
-
405-grain lead bullets: These are readily available, cost-effective, and perform well subsonically.
-
405-grain cast lead bullets: Similar to lead bullets, but often more affordable and with a slightly softer lead alloy that requires more careful attention to seating depth to prevent leading.
-
500-grain lead bullets: Heavier bullets provide better penetration and energy retention. However, they require more powder to reach subsonic velocity.
Sample Subsonic 45-70 Load Data (Disclaimer: This data is for informational purposes only. Always consult published load data from reputable sources before reloading.)
The following table provides example load data. Do not use this data without cross-referencing it with data from your own reloading manuals and using a load scale to verify all charges. Failure to do so could result in serious injury or damage to your firearm.
| Powder | Bullet Weight (grains) | Powder Charge (grains) | Primer | COL (inches) | Notes |
|---|---|---|---|---|---|
| Trail Boss | 405 | 12-15 | Large Rifle | 2.58-2.60 | Start low, work up slowly |
| Unique | 405 | 18-20 | Large Rifle | 2.58-2.60 | Start low, work up slowly |
| IMR 4759 | 405 | 16-18 | Large Rifle | 2.58-2.60 | Start low, work up slowly |
COL refers to Cartridge Overall Length. This dimension should be meticulously measured to ensure proper chambering and safe operation.
Safety Precautions
Reloading ammunition is inherently dangerous. Always adhere to these safety precautions:
- Consult Multiple Loading Manuals: Don't rely on a single source for load data.
- Use a Reloading Scale: Precise powder measurement is critical.
- Wear Safety Glasses: Protect your eyes from potential explosions.
- Work in a Well-Ventilated Area: Gunpowder fumes are harmful.
- Never Exceed Maximum Loads: Overloading is incredibly dangerous.
- Clean your firearm regularly. Failure to do so can cause malfunction and unsafe pressures.
Conclusion
Loading subsonic .45-70 Gov't ammunition offers a unique and rewarding experience for shooters. By understanding the intricacies of powder selection, bullet weight, and the factors influencing velocity, you can safely and effectively achieve subsonic performance. Remember, safety should always be the top priority. Always consult multiple reputable loading manuals and adhere to the provided guidelines to ensure a successful and safe reloading experience. Never compromise on safety when handling firearms or reloading ammunition.