Posted: 9/6/2002 7:53:58 AM EDT
| My buddy and I were discussing from what source the majority of the heat is generated from when one feels heat on the barrel. I say its from friction between the bullet and the barrel. He thinks that its the hot compresed gas. What to you guys think, or more preferabilty, know. |
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Friction. The hot gasses will marginally heat a barrel, it's the friction of the bullet. If he really doubts you, take a round and stuff it in the muzzle, so he can see how tight the bullet fits, and then ask him how much force it takes to push that through the barrel at (insert bullet velocity here/ 2800+fps with a 5.56mm). That would create some heat, wouldn't it? |
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The vast majority of the heat is from the burning powder. The most damage to the rifling is right in front of the chamber where the gasses are hottest. The heat from the burning powder will actually cause a slight vaporization of the bullet base in some cases. Bullet friction plays a small part. Even firing blanks will heat up a barrel. Read "Accurate Rifle" or "Precision Shooting" magazines for more detailed write-ups. |
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"Burning powder and hot gases" is partially correct. The real reason is pressure--lots of it and over a very short time frame. Heat of compression in a very small cavity at seriuosly high pressure generates enormous heat; especially when generated so quickly. For example, we all know when you compress a gas it heats up (air, N2, O2, H2, AR etc.). When filling compressed gas cylinders, over a relatively long period of time, say 1.5 hrs., a a "mere" 2400-2700 psi, the cylinder walls will heat up a great bit. So hot in the summer in fact, that it would be uncomfortable to put your sensitive forearm skin against the wall (but it really wouldn't burn). Much higher pressures are generated in the cylinder known as the chamber/barrel over what amounts to a micro-second. |