Quick Answer
Overpressure in reloads can be identified by excessive primer pocket erosion, cratering, and/or bulging, as well as case head swelling, head separation, and case rupture.
Common Signs of Overpressure
Excessive primer pocket erosion, cratering, and/or bulging are all common signs of overpressure in reloads. To avoid this issue, it’s essential to follow proper powder charge recommendations and be aware of the maximum safe pressure (MSP) for your specific cartridge and rifle combination. A general rule of thumb is to start with a lower than recommended charge and gradually increase it until reaching the desired velocity. This incremental approach helps prevent overpressure and reduces the risk of catastrophic failure.
Causes of Overpressure
Several factors can contribute to overpressure in reloads, including excessive powder charge, incorrect seating depth, and insufficient crimping. Using the wrong propellant or case material can also lead to overpressure. For example, 40-grain H1000 is not suitable for 30-caliber cartridges, whereas 60-grain H1000 can be used with caution. Always consult the data sheet provided by the powder manufacturer and follow the recommended loads carefully. A good rule of thumb is to never use a powder charge that exceeds the recommended maximum by more than 10 percent.
Measuring Pressure
To accurately measure pressure in your reloads, you’ll need a high-pressure gauge or piezoelectric pressure gauge. These gauges can be attached to your barrel or connected directly to the case head to measure the pressure generated by each shot. Be aware that pressure gauges can be sensitive to temperature fluctuations and require proper calibration. Always follow the manufacturer’s instructions for installation, calibration, and use. A pressure reading exceeding 60,000 psi (psi) on a 30-caliber cartridge is considered excessive and may indicate overpressure issues.
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