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Posted: 9/2/2010 1:07:04 PM EDT
| Looking for information on bullet drop, primarily if the bullet rises after it leaves the barrell. I thought I read some threads on here stating it doesn't rise after it leaves the barrell but drops as soon as it leaves the barrell due to gravity. Also it appears to rise because of the line of site in relation to the bore axis. The more I think about it or try to explain it the more I get confused. Got into a debate with a gentleman today and just want to know. My reasoning is that on the boxes of ammo it always shows a arch-bullet path and If I remeber correctly that was because of line of site to line of travel. Also include any references that I can attach to a e-mail or that I can actually explain without sounding confused. Thanks |
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Quoted:
Looking for information on bullet drop, primarily if the bullet rises after it leaves the barrell. I thought I read some threads on here stating it doesn't rise after it leaves the barrell but drops as soon as it leaves the barrell due to gravity. Also it appears to rise because of the line of site in relation to the bore axis. The more I think about it or try to explain it the more I get confused. Got into a debate with a gentleman today and just want to know. My reasoning is that on the boxes of ammo it always shows a arch-bullet path and If I remeber correctly that was because of line of site to line of travel. Also include any references that I can attach to a e-mail or that I can actually explain without sounding confused. Thanks The bullet only rises if the barrel's tilted up above horizontal. In order to compensate for drop at range, sights are calibrated so that the barrel is in fact tilted relative to the plane of the sights or scope, meaning that if you fire at a target very close to the muzzle, the bullet will impact ABOVE the point of aim. At the zero distance, the bullet should hit right at the point of aim, and beyond that, the bullet will impact below the point of aim. |
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Quoted:
Looking for information on bullet drop, primarily if the bullet rises after it leaves the barrell. I thought I read some threads on here stating it doesn't rise after it leaves the barrell but drops as soon as it leaves the barrell due to gravity. Also it appears to rise because of the line of site in relation to the bore axis. The more I think about it or try to explain it the more I get confused. Got into a debate with a gentleman today and just want to know. My reasoning is that on the boxes of ammo it always shows a arch-bullet path and If I remeber correctly that was because of line of site to line of travel. Also include any references that I can attach to a e-mail or that I can actually explain without sounding confused. Thanks Hang on, somebody will shine the Molon Signal in the sky soon and a graphic will appear in this thread that explains it perfectly. |
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All ballistic trajectory data includes a correction factor for the sights being a certain height above the bore axis. Usually the figure is 1.5" for scoped hunting rifles. In order for the trajectory of the bullet (which is an arc) to coincide with the line of sight of the sights (which is a straight line) the barrel needs to be tilted upward at a slight angle.
Think about looking at a target at eye level then throwing an underhand pitch in softball. In order to hit the target you must throw higher than eye level so that the ball hits the target on the downward trajectory. Also note that the ball crosses your line of sight twice. Once on the way up, and then again at the target. Note however that gravity has an effect on the ball regardless of whether you throw it up or in a straight line. Essentialy the ball is always being pulled down, but because it is launched at an upward angle, and has an initial upward velocity it will gain altitude until gravity reduces the upward component to zero (at the top of the arc), and the ball begins to fall downward accelerating downward. So yes the bullet does gain altitude when it is fired. The rise is due to the launch angle being greater than zero by some small amount. Yes gravity begins to act on a bullet the moment it leaves the barrel. |
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