The 10mm Auto cartridge, known for its potent power and versatility, demands careful consideration when it comes to reloading. This guide focuses specifically on load data for the popular Longshot powder, providing detailed information to help you safely and effectively develop your own 10mm loads. Always remember to consult your reloading manual and follow its safety instructions before attempting any reloading. This information is for educational purposes only and should not be considered a substitute for proper training and safety precautions.
Understanding Longshot Powder
Longshot is a relatively slow-burning powder, making it a popular choice for larger handgun cartridges like the 10mm Auto. Its characteristics lend themselves well to achieving high velocities and impressive accuracy, particularly with heavier bullets. However, its slow burn rate requires precise measurements and careful attention to detail to avoid over-pressure. Never exceed the maximum listed charge weight.
Factors Affecting Load Data
Several factors influence the optimal load data for your specific 10mm setup:
- Bullet Weight: Heavier bullets generally require less powder to achieve a specific velocity, while lighter bullets require more.
- Case Capacity: Variations in case capacity between different manufacturers can influence pressure.
- Primer Type: The type of primer used can subtly impact pressure and ignition characteristics.
- Barrel Length: Longer barrels generally produce higher velocities.
- Altitude: Higher altitudes can slightly alter powder burn rates.
Sample Longshot 10mm Load Data (Disclaimer: This data is for illustrative purposes only. Always refer to your reloading manual and your specific components)
Note: The following data is presented as a sample and should never be used without verifying it against your specific reloading manual and components. Variations in components can significantly affect pressure.
| Bullet Weight (grains) | Bullet Type | Powder (Longshot) (grains) | Primer | COL (inches) | Velocity (fps) (Approximate) | Notes |
|---|---|---|---|---|---|---|
| 180 | FMJ | 7.5 | Large Pistol | 1.250 | 1100 | Start load - work up carefully |
| 180 | FMJ | 8.0 | Large Pistol | 1.250 | 1150 | |
| 180 | FMJ | 8.5 | Large Pistol | 1.250 | 1200 | Maximum load - Do not exceed |
| 200 | JHP | 7.0 | Large Pistol | 1.260 | 1050 | Start load - work up carefully |
| 200 | JHP | 7.5 | Large Pistol | 1.260 | 1100 | |
| 200 | JHP | 8.0 | Large Pistol | 1.260 | 1150 | Maximum load - Do not exceed |
COL refers to Cartridge Overall Length. This measurement is critical for consistent performance and safety.
Developing Your Loads: A Step-by-Step Guide
- Start Low, Go Slow: Begin with the minimum listed charge weight in your reloading manual.
- Work Up Gradually: Increase the powder charge in small increments (0.2 grains is a common increment).
- Chronograph Your Loads: A chronograph is essential for accurately measuring velocity and ensuring consistent performance.
- Observe Cases for Pressure Signs: Carefully examine fired cases for signs of excessive pressure, such as flattened primers, bulged cases, or excessive case head expansion.
- Document Everything: Keep a detailed log of your load data, including bullet weight, powder charge, primer type, velocity, and any observations.
- Clean Your Equipment: Maintaining clean reloading equipment is crucial for consistent performance and safety.
Safety First: Crucial Reminders
- Always wear safety glasses and hearing protection.
- Never mix powders.
- Never exceed maximum listed charge weights.
- Properly lubricate your cases.
- Check your loaded rounds for proper seating and crimp.
- Handle loaded ammunition with care.
This information is intended for experienced reloaders familiar with safe reloading practices. Newcomers to reloading should seek out formal training and guidance from experienced reloaders before attempting to load any ammunition. Improper reloading techniques can lead to serious injury or death. Always consult your reloading manual and follow its instructions carefully.
