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Posted: 12/6/2008 7:34:09 PM EDT
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Hi,
I have read that the army change their AR barrels every 5-7k rounds ( I understand they shoot full auto), and most guys on other forum will change their barrel before it reach 10k rounds, But when it comes to pistols, people are shooting them up to 50K-75K and even 100K. So can somebody explain to me why? Thanks. |
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Bottleneck rifle cartridges have very high propellant volumes relative to the bore volume. This allows them to burn a lot of powder behind a little bullet, creating high pressures and velocities.
This results in high gas temperatures, leading to high surface metal temperatures, which increases susceptibility to erosion. It also results in large volumes of gas/solid mixtures rushing over these hot surfaces at very high velocities, causing the erosion. I have heard that short lifespan is common on the carbines, but I believe the rifles are still usually getting well over 10k rounds out of the barrels, even in US military service. Semi-auto AR rifles are probably mostly capable of 20k-30k. |
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