Quick Answer
Overall length can impact chambering reliability by affecting the cartridge's fit within the rifle's chamber, particularly with longer cartridges. A cartridge that's too long may not fully seat when chambered, while one that's too short may bind or jam. Proper overall length is critical for reliable feeding and extraction.
Cartridge Length Considerations
When hand loading hunting cartridges, the overall length must be carefully managed to ensure reliable chambering. A general rule of thumb is to keep the cartridge overall length (COL) between 0.015 and 0.030 inches shorter than the chamber’s maximum length. This allows for proper seating and extraction of the cartridge. For example, a .308 Winchester cartridge should have a COL of 2.015 to 2.035 inches in a standard chamber.
Chamber Tolerances and Reliability
Chamber tolerances play a significant role in determining the reliability of cartridge chambering. A chamber with tighter tolerances (e.g., SAAMI minimums) may not accommodate longer cartridges, while looser tolerances (e.g., SAAMI maximums) may allow for longer cartridges but may also lead to increased wear and potential reliability issues. When hand loading, it’s essential to understand the chamber’s tolerances and adjust the overall length accordingly.
Best Practices for Measuring and Adjusting Overall Length
To ensure accurate and reliable chambering, it’s crucial to measure the overall length of each hand-loaded cartridge carefully. A good quality caliper or micrometer should be used to take precise measurements. When adjusting the overall length, it’s essential to start with a longer cartridge and trim it to the desired length rather than trying to add length to a shorter cartridge. This approach helps avoid over-trimming and subsequent reliability issues.
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