Vern Humphrey
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And, depending on the scope, less parallax at the longer range.After the bullet has stabilized, it's less affected by external forces.
Is it possible for a rifle to be more accurate at distance than 100 yards?
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Barrels whip and wiggle while bullets go through them just like fishing rods when smacked with some external force.
http://www.varmintal.com/amode.htm
It's not effected any different by gravity or wind. Those are the only external forces. Unless it's a steel bullet and flies close to a magnet.
Llama Bob
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This thread shows a remarkably poor grasp of external ballistics in general. If you shoot in a wind-free environment at a close paper-only target, and then have the bullets pass through it to strike a second, more distant target the groups will always get larger on the second target. This is easy to test on an indoor 100y range with 25y and 100y targets shooting rimfire (which mimics longer ranges with centerfire).
Outdoors, you sometimes get a situation where wind will cancel muzzle dispersion, and as a result you'll see a smaller group on the farther target. But it's a small effect, and it never happens consistently, only randomly. Measure the average group, and they always get bigger.
Outdoors, you sometimes get a situation where wind will cancel muzzle dispersion, and as a result you'll see a smaller group on the farther target. But it's a small effect, and it never happens consistently, only randomly. Measure the average group, and they always get bigger.
So then, you must not believe in positive compensation for far range bullet drop when bullets leave on the muzzle axis up swing.
And then tuners on barrels used to refine barrel whip to make compensation better is unscientific voodoo.
Where's my Llama Bob doll? I just sharpened all my pins. My voodoo suit just got back from the cleaners and I'm donning it as I type.........
This thread shows a weak grasp of external, and internal, ballistics coupled with barrel mechanics in general.
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Llama Bob
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I believe you have no clue what you're talking about, Bart. This has been repeatedly tested, and at this point is a well established fact of exterior ballistics. All the people who thought they could make groups shrink at range were invited to provide evidence, and none could.
That's fine with me. Thousands of others think the same as I. We understand your disbelief.
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/tuning_a_barrel.htm
http://forum.accurateshooter.com/th...-a-long-range-shooter-can-understand.3920005/
The fact that the Brits dealt with it for over 5 decades with their SMLE 303's loaded with Cordite producing huge muzzle velocity spreads but shooting smaller groups past 800 yards than at medium ranges has no bearing whatsoever.
I don't think you understand why and how barrels wiggle while bullets go through them versus bullets' barrel time across muzzle velocity spread.
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wally
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Grab your SMLE and stash of .303 Cordite loads and get win free all expenses paid trip to Brian Litz's lab/range to prove him and the rest of us wrong!
Mr A. Mallock ("Vibrations of Rifle Barrels", Proceedings of the Royal Society, Vol. 68, page 327, 1901) may not have been the first person to put forward the proposition that a rifle can be "tuned" to generate "positive compensation" at a given range, but it shows that this idea has been around for well over a century and is not a new one.
The proposition for positive compensation is based on the fact that when any given batch or type of ammunition is chronographed, there is a always a spread in muzzle velocity observed about a mean. As a consequence, there will be a vertical dispersion in the fall of shot at the target, as the slower bullets in the sample take longer to travel down the range and so drop further than the faster bullets. It is easy to compute what the vertical dispersion should be for a given batch of ammunition due to the observed spread in muzzle velocity.
Curiously though, it is also often - if not usually - observed that the calculated vertical dispersion is not evident on the target. To explain this observation, the concept of "positive compensation" is invoked. It is generally recognised that the shock of the recoil forces in the rifle generate transverse vibrations in the barrel. For positive compensation, it is envisaged that the bullet is exiting the muzzle during an upward swing in the vibration at the muzzle, such that faster bullets (which arrive at the muzzle slightly earlier than slow bullets) are launched at a slightly lower angle into their trajectory than slower bullets. This will tend to reduce the vertical dispersion in the group at the target resulting from the variation in muzzle velocity. And if the upward swing in the muzzle is exactly right, there will be complete positive compensation as the trajectories of bullets across the entire spread of muzzle velocities all meet at the same height on the target at a given range...
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/tuning_a_barrel.htm
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/velocity_dispersion.htm
Am I the only one in this place that understands the principle of positive compensation and has shown proof it exists?
The proposition for positive compensation is based on the fact that when any given batch or type of ammunition is chronographed, there is a always a spread in muzzle velocity observed about a mean. As a consequence, there will be a vertical dispersion in the fall of shot at the target, as the slower bullets in the sample take longer to travel down the range and so drop further than the faster bullets. It is easy to compute what the vertical dispersion should be for a given batch of ammunition due to the observed spread in muzzle velocity.
Curiously though, it is also often - if not usually - observed that the calculated vertical dispersion is not evident on the target. To explain this observation, the concept of "positive compensation" is invoked. It is generally recognised that the shock of the recoil forces in the rifle generate transverse vibrations in the barrel. For positive compensation, it is envisaged that the bullet is exiting the muzzle during an upward swing in the vibration at the muzzle, such that faster bullets (which arrive at the muzzle slightly earlier than slow bullets) are launched at a slightly lower angle into their trajectory than slower bullets. This will tend to reduce the vertical dispersion in the group at the target resulting from the variation in muzzle velocity. And if the upward swing in the muzzle is exactly right, there will be complete positive compensation as the trajectories of bullets across the entire spread of muzzle velocities all meet at the same height on the target at a given range...
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/tuning_a_barrel.htm
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/velocity_dispersion.htm
Am I the only one in this place that understands the principle of positive compensation and has shown proof it exists?
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denton
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Llama Bob
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Bart, it makes no difference what explanation you or anyone else makes up for a given phenomenon IF THEY CAN'T DEMONSTRATE IT HAPPENS IN THE FIRST PLACE. If you show a rifle/load combination that produces smaller groups by angular measurement at range in a double target configuration, you will be the first one to do so. Everyone who thought they could do so (and there were initially many) has had to admit they were wrong after actually trying it.
There's no point in arguing what causes the coloration of a pink unicorn, if no one can provide evidence pink unicorns exist.
There's no point in arguing what causes the coloration of a pink unicorn, if no one can provide evidence pink unicorns exist.
Snyper
Member
You just keep repeating yourself when what you're saying has nothing to do with what everyone else is talking about.
Barrel harmonics can make a difference in accuracy.
It can't make a gun shoot a smaller group at a longer distance than it will at a shorter distance.
It improves accuracy equally at all distances.
No one has disputed that fact.
It simply has nothing to do with this topic.
You're the only one who thinks it relates to what is being discussed.
Nature Boy
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Bart,
Do you still shoot?
Do you still shoot?
denton
Member
Bart, not to offend your good self, but that is not at all how the BOSS works.
The BOSS shrinks groups both horizontally and vertically. If it worked by compensating for differences in bullet drop, it would only shrink them vertically.
The barrel typically vibrates both horizontally and vertically, probably in an elliptical arc. The BOSS changes the resonant frequency of the barrel so as to time the bullet exit to be near a slow moving part of the arc. Bullets that exit near this time will group more tightly than bullets that exit during a fast moving part of the arc. This happens for two reasons: 1) The barrel is pointing in nearly the same direction in spite of variations in bullet transit times, and 2) The slow moving part of the arc imparts less transverse speed to the bullet.
The BOSS shrinks groups both horizontally and vertically. If it worked by compensating for differences in bullet drop, it would only shrink them vertically.
The barrel typically vibrates both horizontally and vertically, probably in an elliptical arc. The BOSS changes the resonant frequency of the barrel so as to time the bullet exit to be near a slow moving part of the arc. Bullets that exit near this time will group more tightly than bullets that exit during a fast moving part of the arc. This happens for two reasons: 1) The barrel is pointing in nearly the same direction in spite of variations in bullet transit times, and 2) The slow moving part of the arc imparts less transverse speed to the bullet.
HoosierQ
Member
Rifle? No. Optics, quite likely if this is a real problem.
Steve Cover
Member
There are a lot more forces at work...
MASS FORCES
Gravity
Coriolis Force
Centrifugal force
AERODYNAMIC FORCES
Drag
Lift (Cross Wind Force)
Magnus
Transverse Magnus
Pitch Damping (What makes the cone of accuracy shrink as distance increases)
So yes, a properly stabilized bullet will have a decreasing cone of accuracy as it stabilizes out...
Here are the basics:
http://ffden-2.phys.uaf.edu/212fall2001_Web_projects/Isaac Rowland/Ballistics/Bulletflight/index.htm
Hope this helps...
Steve
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denton
Member
Gravity: Listed in my post.
Coriolis Force: A real factor, but not a real force. It's a fictitious force that arises from the fact that Earth is not a true inertial reference frame.
Centrifugal Force: An internal force, not an external one. Can't change the path of the bullet, per Isaac Newton.
Drag: Listed in my post.
Lift: Vector component of drag.
Magnus Force: Exceedingly tiny, but real.
Transverse Magnus Force: Vector component of Magnus Force.
Pitch damping: Vector component of drag.
Mn Fats
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What is this? Prove Bryan Litz wrong. He'll pay you for it. People are stuck in their thinking on this but Mr. Litz is literally putting his money where his mouth is. So? Pony up and prove him wrong. You naysayer's don't have a free Saturday? Make history with the .303 and Litz. Its all words but his challenge still stands. Edit to say, optics are the factor in this phenomenon. Period.
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redbullitt
Member
I dont think so. Doesnt make sense to me why the OP question would ever happen.
Steve Cover
Member
All of the physics are real.... Their effect is minute, but still true... A properly stabilized bullet will settle into a small cone of variation over time... While better optics will increase the accuracy, they have no effect on the bullet and that is how I interpreted the question.
Fats are you a pool player?
Back in the day when I took it seriously, I was known as Mr. C.
Paid for a Brunswick Gold Crown and a Preditor cue...
Steve
Steve Cover
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