quote:

Because to be honest, the way you wrote it doesn't make a lick of sense.

Go back to physics class and pay attention this time!

quote:

...at the range with our M16s, if the target at 15 meters popped up..if you aimed right at it and pulled the trigger, you'd shoot right over it...Happened every time...

Hopefully there was a lot of tongue-in-cheek with that post. My current CAR-15 shoots slightly low at 15 yards when zeroed for 150 with issue sights...just like my M-16 did in 1970. Try it, it has to be because of the very high sight line on these rifles.

quote:

Because to be honest, the way you wrote it doesn't make a lick of sense.

A little less harshly, the principle is identical: two objects dropped at the same time hit the ground at the same time; horizontal displacement makes no difference because the vectors are independent of each other. Actually a bullet can create some small amount of lift as it travels through the air depending on its shape and the amount of stabilization it is given (flying with an angle of attach), so that could throw off the experiment a skosh. But Newton was right.

http://dsc.discovery.com/video...vs-fired-bullet.html



.

Didn't Newton allow for the deviation caused by lift? If I recall correctly (and at this age I might not), didn't he posit the two objects falling in a vacuum? No lift caused by jnteraction of plane surfaces with air in a vacuum.

Si? No?

Snyway, the points are valid. If the bullet was fired over a perfectly flat surface, it would strike the flat surface at the same time as a bullet dropped onto it. So would a pound of feathers, if both were fired/dropped in a vacuum.

And no, Virginia, bullets do not rise relative to the line of the bore after exit. They start to fall the instant they no longer are held up by the barrel....again, assuming they are fired in a vacuum and thus have no operating lift surfaces. For all practical purposes it is true even if not in a vacuum, as any lift created is so small as to be negligable.

Cheese and crackers!! Doesn't anybody listen in school science classes anymore?

Or is all science now an "elective", which I take it these days means a class one doesn't have to take if he fears it may cause him to both have to learn and to think?

One of the nice things about my high school days was that to graduate, ALL students had to take 2 years of a foreign language, 4 years of history (2 years of U.S. history and 2 years of world history), 4 years of English, 4 years of math, and 4 years of science (chemistry, physics, botany and biology...geology could be substituted for botany).

University was pretty much the same thing, at more advanced levels, except as a junior and senior one could declare a "major" and one or more "minors" and take as many classes as they could stand in those subjects...and computer science was added to the required classes just a few years after I graduated.

Davis Goertzen--When you drop a bullet it wont make the fired bullet tumble out the end--wont have any effect--gun will still shoot. What Mr Newton was saying is that fired bullet, zipping along will have the same force of gravity acting upon it as what the dropped bullet--not zipping along has on it. So the two bullets will hit at the same time but how far away zippy will be is based on characteristics of the bullet and it's muzzle velocity--it doesn't gain speed as it goes--it is losing speed from the instance it leaves the muzzle. Does that make sense?

interesting debate with a lot of people thinking bullshit.... gravity is equal and constant.................

Intuitive thnking on the basis of what works over here should work over there often leads to invalid thinking.

To do the test of Newton's theory ( correct it is ) you need a flat field which is exactly a chord to the radius from the centre of the earth then you have to set the firearm barrel EXACTLY perpendicular to the radius of the earth at one end of the chord.

Even with theodolite and exacting setup you will struggle to set that barrel up accurately enough .

To prove the point that AS made, you do that same setup at the edge of a lake on a sleeky calm day ( knowing there is nothing on the opposite shore other than a cliff.
fire at will
note the time difference between the 2 splashes........easy to do with your average digital camera reviewed frame by frame.
But then you have to understand that water level is not flat in a body of water..........it actually curves to the average radius of the earth at the location height you are doing your test at.
With the barrel set perp to the earth's radius the curvature of that body of water will fall away in a curve at the average radius of the earth from the line of sight of the barrel, because your barrel is aiming at a tangent to the circumference of the earth.

anyone who thinks that the water surface is flat needs to think again & toddle down to the local 50M swimming pool with a theodolite & laser level & set up reference points at each end the same height above the water surface & measure the water height relative to the laser line at the middle of the pool. A surveyor can do that accurately enough over 50M to show you that the water surface when dead calm in that pool is actually curved over the length of the pool..............the water DOES NOT form a chord between the two ends..........it obeys Newtons gravitational laws,so it has to curve.
If it didn't everyone of us on the earth would be in deep do-do.

Small moonpools with decent waterflow levels are dead flat at the overflow end.
larger ones are not..........if its flat the water overflow does not cover the edge of the overflow.

Moonpool builders discover firsthand all about gravity, waterlevel & gravitational forces on their first attempt at a moonpool , they always build the overflow exactly flat & discover it doesnt work .
He He....... what happens then is the builder upgrades the circulation pump to increase water flow till it reaches the edges ........then makes all sorts of excuses why the customer needed to pay for an upgraded circulation pump.
Building that overflow edge of a large moonpool to the curvature required is a PITA.

Now you know why large length overflows on moonpools are like hen's teeth .........too hard to construct accurately.

Wondered why the moonpool edge of the 9/11 monument is fluted, now you know that too.
much easier to align each fluted segment & the water column height flowing out each segment covers up innacuracies in the flat alignment of the short sections that are joined together to simulate a curved length.

Build a large wonderfully flat concrete floor & wonder why water always pools in the middle.......now you know the answer to that too.

Rice growers with very large capacity paddies , requiring exact water depth for uniform growth have the same issues preparing their paddies prior to flooding. Small paddies no big deal.

Physics 101.........

All of this high tech stuff is very interesting but the simple fact remains that the barrel of the rifle is oriented upward relative to the the line of sight of the sights. Thus it gives the illusion of the bullet rising as it leaves the rifle.

Aside to AC. I can remember back with kids going to school were expected to get an education in order to graduate.

I used to think it was BS, untill I talked to an engineer in aircraft weaponery, who told me that on airplanes, the Magnus effect could make a bullet rise at some point of it's trajectory.

Magnus effect IIRC is in the plane of spin ie golf balls, curve balls/cutters etc so it'd effect windage not elevation.

Not a science experiment -> air. It's drag v. gravity in elevation changes and drag is multifactorial.

Remember, the majority of people in this world are mouth breathers-the dumbass ratio is about 1000:1

Frankly, I'da just looked at the situation and the person you're dealing with and win the argument......yes dear, you're absolutely right. and walk away thinking fn idiot.

Ya'll might want to take a read here... http://www.frfrogspad.com/extbal.htm ... or search for "A Short course on External Ballistics" depending on your level of need to actually understand and comprehend External Ballistics... and do a bit of online research on bullet lift, bullet precession, parabolic curves, Newtonian physics, gravity...etc.

Magnus effect from Wikipedia:

"Magnus force from the crosswind would cause an upward or downward force to act on the spinning bullet (depending on the left or right wind and rotation), causing an observable deflection in the bullet's flight path up or down, thus changing the point of impact."


Of course...I wouldn't want ugly facts to interfer with a beautiful mis-understanding...

Luck

All this drop theory is only valid north of the equator. In the southern hemisphere it reverses; bullets rise as they fly. The rate of change occurs at an acclerated rate as we near the pole and the bullets will eventually exit into space through the antartic ozone hole.
------------------------------------------


Or; Gravity isn't just a good idea, it's a law.

quote:

Originally posted by Jim C. <><:
All this drop theory is only valid north of the equator. In the southern hemisphere it reverses; bullets rise as they fly. The rate of change occurs at an acclerated rate as we near the pole and the bullets will eventually exit into space through the antartic ozone hole.
------------------------------------------
Or; Gravity isn't just a good idea, it's a law.

you can talk about it.
Us peoples 'downunda' in Oz have been hanging on to the dear earth with our toes the whole of our lives..............its tiring.


Back in the real world most physical effects we see are influenced by a number of parameters.
some big, some small.
some have effects so small its difficult to see them.
The biggies that dominate the issues discussed here are:-
- gravity
- projectile launch orientation
- velocity
( in general ballistics)

and
- the curvature of the earth / orientation of what you think is your flat surface.....if you are playing with falling apples theory

The rest have piffling effects that could under some circumstances affect the accuracy of the end result ...........but not the overall path.
That path is downwards from the orientation of the barrel in any practical hunting/shooting situation.

- SD
- BC
- wind
-spin
- humidity
- altitude
- coriolis effect
- magnus effect etc
are all in the piffling category that affect the accuracy of the result not the overall result.

If your line of sight is not the same orientation as the barrel the only thing that is affected is the impact point of the projectile relative to the line of sight along that trajectory, not any of the physics that dominate the determination of that trajectory.

I say again...over...

"I wouldn't want ugly facts to interfer with a beautiful mis-understanding..."

Luck

quote:

Originally posted by Davis Goertzen:

quote:

Originally posted by carpetman1:
If a gun is held perfectly level and fired over level ground, and at same instance it is fired another bullet of the same weight is dropped from the same height as the rifle, the two bullets will hit at the same time. Hard to believe but the person to argue about it is no longer available--it was Sir Issac Newton.

No disrespect intended, but I'm seriously hoping that I totally missed your point here. From what I understand you to say, shooting a gun shouldn't work at all, because the bullets would just tumble out of end of the barrel and hit the ground forthwith. Anyone who's shot even a pellet gun or a 22 knows it ain't so. Even an arrow from a bow, only going a few hundred fps, can fly through the air and overcome gravity for a little while.

I think the experiment you referred to actually had to do with 2 differently weighted objects (cannonballs I think?), and the point was that when dropped from the same height, they would hit the ground at the same time.

Maybe can you elaborate on what you're driving at here? Because to be honest, the way you wrote it doesn't make a lick of sense.

Davis

No, the time of falling is the same for a fired bullet and a dropped bullet. If it takes 1 second for the dropped bullet to hit the ground it will take 1 second for the fired bullet to hit the ground also.

During that 1 second, the fired bullet will have travelled 500 yards or so but it will still hit the ground at the same time.

Yes, Frank, correct. Also because gravity effects the bullet in the vertical plane, it is the distance travelled horizontally upon which gravity effects bullet flight- why you hold for the horizontal distance and not the vertical on an up/downhill shot.


PS Interesting read, thanks. I just knew about it from golf- clubmaking & shaft/clubhead effects on ball spin.

But in reading this it sounds like it mainly effects moyels who practice their profession on gnats at 100yds.

But here it is for all:

The Magnus effect can also be found in advanced external ballistics. Firstly, a spinning bullet in flight is often subject to a crosswind, which can be simplified as blowing either from the left or the right. In addition to this, even in completely calm air a bullet experiences a small sideways wind component due to its yawing motion. This yawing motion along the bullet's flight path means that the nose of the bullet is pointing in a slightly different direction from the direction in which the bullet is travelling. In other words, the bullet is "skidding" sideways at any given moment, and thus it experiences a small sideways wind component in addition to any crosswind component.[13]

The combined sideways wind component of these two effects causes a Magnus force to act on the bullet, which is perpendicular both to the direction the bullet is pointing and the combined sideways wind. In a very simple case where we ignore various complicating factors, the Magnus force from the crosswind would cause an upward or downward force to act on the spinning bullet (depending on the left or right wind and rotation), causing an observable deflection in the bullet's flight path up or down, thus changing the point of impact.

Overall, the effect of the Magnus force on a bullet's flight path itself is usually insignificant compared to other forces such as aerodynamic drag. However, it greatly affects the bullet's stability, which in turn effects the amount of drag, how the bullet behaves upon impact, and many other factors. The stability of the bullet is impacted[citation needed] because the Magnus effect acts on the bullet's centre of pressure instead of its centre of gravity. This means that it affects the yaw angle of the bullet: it tends to twist the bullet along its flight path, either towards the axis of flight (decreasing the yaw thus stabilizing the bullet) or away from the axis of flight (increasing the yaw thus destabilizing the bullet). The critical factor is the location of the centre of pressure, which depends on the flowfield structure, which in turn depends mainly on the bullet's speed (supersonic or subsonic), but also the shape, air density and surface features. If the centre of pressure is ahead of the centre of gravity, the effect is destabilizing; if the centre of pressure is behind the centre of gravity, the effect is stabilizing.[citation needed

Back when the world was flat before Columbus invented a round world, this stuff was simple. Bullets travelled a lot further. Have you ever heard of ANYONE missing a 5 mile shot with a 30-06 before Columbus came along? See what I mean?

quote:

you can talk about it.
Us peoples 'downunda' in Oz have been hanging on to the dear earth with our toes the whole of our lives..............its tiring.

I have always held you folk in high regard for your persistance in the face of great difficulty. One of your erstwhile Oz-mates lives next door, says he had to walk on his hands the first six months he was here - but that was over long before I met him. He's confirmed the ballistics thing I mentioned earlier so I know it's true.

quote:

Originally posted by FMC:
Yes, Frank, correct. Also because gravity effects the bullet in the vertical plane, it is the distance travelled horizontally upon which gravity effects bullet flight- why you hold for the horizontal distance and not the vertical on an up/downhill shot.


PS Interesting read, thanks. I just knew about it from golf- clubmaking & shaft/clubhead effects on ball spin.

But in reading this it sounds like it mainly effects moyels who practice their profession on gnats at 100yds.

But here it is for all:

The Magnus effect can also be found in advanced external ballistics. Firstly, a spinning bullet in flight is often subject to a crosswind, which can be simplified as blowing either from the left or the right. In addition to this, even in completely calm air a bullet experiences a small sideways wind component due to its yawing motion. This yawing motion along the bullet's flight path means that the nose of the bullet is pointing in a slightly different direction from the direction in which the bullet is travelling. In other words, the bullet is "skidding" sideways at any given moment, and thus it experiences a small sideways wind component in addition to any crosswind component.[13]

The combined sideways wind component of these two effects causes a Magnus force to act on the bullet, which is perpendicular both to the direction the bullet is pointing and the combined sideways wind. In a very simple case where we ignore various complicating factors, the Magnus force from the crosswind would cause an upward or downward force to act on the spinning bullet (depending on the left or right wind and rotation), causing an observable deflection in the bullet's flight path up or down, thus changing the point of impact.

Overall, the effect of the Magnus force on a bullet's flight path itself is usually insignificant compared to other forces such as aerodynamic drag. However, it greatly affects the bullet's stability, which in turn effects the amount of drag, how the bullet behaves upon impact, and many other factors. The stability of the bullet is impacted[citation needed] because the Magnus effect acts on the bullet's centre of pressure instead of its centre of gravity. This means that it affects the yaw angle of the bullet: it tends to twist the bullet along its flight path, either towards the axis of flight (decreasing the yaw thus stabilizing the bullet) or away from the axis of flight (increasing the yaw thus destabilizing the bullet). The critical factor is the location of the centre of pressure, which depends on the flowfield structure, which in turn depends mainly on the bullet's speed (supersonic or subsonic), but also the shape, air density and surface features. If the centre of pressure is ahead of the centre of gravity, the effect is destabilizing; if the centre of pressure is behind the centre of gravity, the effect is stabilizing.[citation needed

.



When you copy something you've Googled and paste it here, you should use the "quote" function at the top of reply bar.

Otherwise it's plagiarism

quote:

Originally posted by rcamulia:

quote:

Originally posted by FMC:
Yes, Frank, correct. Also because gravity effects the bullet in the vertical plane, it is the distance travelled horizontally upon which gravity effects bullet flight- why you hold for the horizontal distance and not the vertical on an up/downhill shot.


PS Interesting read, thanks. I just knew about it from golf- clubmaking & shaft/clubhead effects on ball spin.

But in reading this it sounds like it mainly effects moyels who practice their profession on gnats at 100yds.

But here it is for all:

The Magnus effect can also be found in advanced external ballistics. Firstly, a spinning bullet in flight is often subject to a crosswind, which can be simplified as blowing either from the left or the right. In addition to this, even in completely calm air a bullet experiences a small sideways wind component due to its yawing motion. This yawing motion along the bullet's flight path means that the nose of the bullet is pointing in a slightly different direction from the direction in which the bullet is travelling. In other words, the bullet is "skidding" sideways at any given moment, and thus it experiences a small sideways wind component in addition to any crosswind component.[13]

The combined sideways wind component of these two effects causes a Magnus force to act on the bullet, which is perpendicular both to the direction the bullet is pointing and the combined sideways wind. In a very simple case where we ignore various complicating factors, the Magnus force from the crosswind would cause an upward or downward force to act on the spinning bullet (depending on the left or right wind and rotation), causing an observable deflection in the bullet's flight path up or down, thus changing the point of impact.

Overall, the effect of the Magnus force on a bullet's flight path itself is usually insignificant compared to other forces such as aerodynamic drag. However, it greatly affects the bullet's stability, which in turn effects the amount of drag, how the bullet behaves upon impact, and many other factors. The stability of the bullet is impacted[citation needed] because the Magnus effect acts on the bullet's centre of pressure instead of its centre of gravity. This means that it affects the yaw angle of the bullet: it tends to twist the bullet along its flight path, either towards the axis of flight (decreasing the yaw thus stabilizing the bullet) or away from the axis of flight (increasing the yaw thus destabilizing the bullet). The critical factor is the location of the centre of pressure, which depends on the flowfield structure, which in turn depends mainly on the bullet's speed (supersonic or subsonic), but also the shape, air density and surface features. If the centre of pressure is ahead of the centre of gravity, the effect is destabilizing; if the centre of pressure is behind the centre of gravity, the effect is stabilizing.[citation needed

.



When you copy something you've Googled and paste it here, you should use the "quote" function at the top of reply bar.

Otherwise it's plagiarism

+1

I feel the same way about pictures too. Credit should be given when due.

Terry

After reading all the posts what matters to me is that my old 270 Win rifle with a 4X scope ,purchased in 1952,shooting 130 Gr bullet hand loads, the bullet will hit below the line of site out to about 30 yards, the bullet will hit about three inches above the line of site at 100 yards and about six inches low at 300 yards. Found that out back when I was a teenager shoting a various ranges. That old rifle has shot ,pronghorn, mule deer, elk ,and some unwonted critter. Hold into the wind ,know where the bullet will hit at various ranges from your rifle and take home the critters. All the rest IS BS.

I had forgotten about Magnus, but from now on when I am asked when I am shooting long range, 6-1000yds, I adjust elevation as well as wind I'll just say I am applying the Magnus touch. Sounds impressive and will bring about much conversation. Seems like I heard also that on this planet at least, all things in flight travel in a curved path?? Figure gravity and air resistance has something to do with that.

quote:

"Magnus force from the crosswind would cause an upward or downward force to act on the spinning bullet (depending on the left or right wind and rotation), causing an observable deflection in the bullet's flight path up or down, thus changing the point of impact."

Mr Magnus was driving me crazy for a couple of years until some wise old shooter expained him to me. There is a great chart and explination on it in the Long Range Forum.

Not plagiarism unless you claim the information as YOURS...putting the information in quotes and/or referencing the source takes it out of plagiarsm...I did both...copyright infringement is another story.

You could say rca infringed on my infringement when he posted almost the full details and DIDN'T referency my contribution and TC1 did the same thing when he posted rca and didn't reference MY original reference. Kinda like the pot calling the kettle black...

It really doesn't mean squat doodly in the real world as fiddling with your sights adjusts out any variations over the yardage...basically just whanger waving at minutia..."I know more than you do" stuff and of value only to th "elites of the Long Range"...

Totally unrepeatable or unreproducable because weather conditions and other effects are continuously changing even as the bullet is moving downrange. There is no place on earth or in space that all the various effects can be cancelled out to be able to reproduce any shot at will to actually test the various "theories".

Therein/wherein lies the conundrum of the continuous argument without an answer.

ALL ballistics drop tables use forumulas that include a simple or complicated gravity forumula and a distance/time part which anyone who wants to can find on Wikipedia and do the simple calculations.

frfrogspad.com gives most of the answers to the question posited here without the need to wear gaitors to save your boots/pants/shirt and Wikipedia finishes up.

Much of the hoohaa centers around bringing into this question information that has very little or NO bearing on small arms and only infringes into ballistics on the larger scale, like artillery or missles and just slightly into long range, 1000 yd or more shooting and even then most people don't have the correct equipment to actually measure or use any information they might/think they have acquired...no diss or flame intended...what a person perceives as true have a very large impact on any learning...sooo...mis, dis information abounds.

Anyone wishing to climb out of the rut OR understand, however simply or compicated, can do so easy enough...those that don't...won't... ain't no thang, man.

Luck

quote:

Originally posted by FOOBAR:
Not plagiarism unless you claim the information as YOURS...putting the information in quotes and/or referencing the source takes it out of plagiarsm...I did both...copyright infringement is another story.

My suggestion was directed to FMC.

Davis[/QUOTE]

No, the time of falling is the same for a fired bullet and a dropped bullet. If it takes 1 second for the dropped bullet to hit the ground it will take 1 second for the fired bullet to hit the ground also.

During that 1 second, the fired bullet will have travelled 500 yards or so but it will still hit the ground at the same time.[/QUOTE]

Jumping in a little late to the party here, I think what causes most people difficulty is that the terms of statements like this are not defined or when they are people don't realize the significance.

The above statement is false.

If you modify it like this it's true:

No, the time of falling is the same for a fired bullet (fired perfectly horizontally) and a dropped bullet. If it takes 1 second for the dropped bullet to hit the ground it will take 1 second for the fired bullet (fired perfectly horizontally) to hit the ground also.

If you aim the rifle barrel upward it will take longer for the fired bullet to hit the ground than the dropped bullet, if you aim the rifle barrel downward it will take less.

It's true that a projectile begins to fall from the line of bore immediately after it leaves the barrel, however it is NOT true that it begins to fall immediately in the context that most people think of when the subject of rise or fall is discussed, i.e. relative to it's line of sight.

When people watch a motorcycle jump they don't think "look it's falling the instant that it left the ramp" - they think "did you see that?!? That motorcycle got 30' up in the air!" Folks that insist that bullets are falling the instant they are fired are the equivalent of saying the motorcycle never flew up in the air - you may have think it did, but you don't understand physics - he was falling the whole time he left the ramp...

People who insist on discussing ballistics only in terms of line of bore lose folks because they insist that the bullet does not rise, when quite clearly it does rise, relative to it's line of sight - regardless of the fact that it is dropping away from the line of bore.

Who cares if it's dropping below the line of bore? You can't see the line of bore projected - what you can see is the line of sight and the bullet does quite clearly come out below the line of sight, rise above it and fall back down.

David

cananez69--You seem to be missing the part about held perfectly level and level ground--that excludes pointing it up.

quote:

Originally posted by carpetman1:
cananez69--You seem to be missing the part about held perfectly level and level ground--that excludes pointing it up.

Not missing it at all - pointing out that when statements like that are made without the terms being defined it causes comprehension difficulty (yes, I saw the quote within the quote that he was responding to.)

Further pointing out that I think discussing ballistics relative to line of bore is silly because most people are thinking in terms of line of sight. If you aren't including qualifiers (line of sight or line of bore) in your discussion point then most people assume line of sight.

David

quote:

Originally posted by Cary Howard:
I shoot guns at a few local gun clubs and I have a range at my house and I always hear guys saying that bullets rise. I always just pretend that I didnt hear them and go on about my business. Wednesday I was shooting with a couple of my buddies and one tells the other that when you shoot a gun the bullet comes out and immediately drops and then begins to rise then it starts to drop again!!!! I asked him to explain to me how in the hell could a bullet do that!!!! The answer I got was that "the Marine Core snipers say that, and that is the way it is." Somebody please tell me that all these guys saying that a bullet will rise, are full of crap! If I am wrong please explain how the hell it does it!!!!!

Here's the original post.....just for clarification!

quote:

Originally posted by vapodog:

quote:

Originally posted by Cary Howard:
I shoot guns at a few local gun clubs and I have a range at my house and I always hear guys saying that bullets rise. I always just pretend that I didnt hear them and go on about my business. Wednesday I was shooting with a couple of my buddies and one tells the other that when you shoot a gun the bullet comes out and immediately drops and then begins to rise then it starts to drop again!!!! I asked him to explain to me how in the hell could a bullet do that!!!! The answer I got was that "the Marine Core snipers say that, and that is the way it is." Somebody please tell me that all these guys saying that a bullet will rise, are full of crap! If I am wrong please explain how the hell it does it!!!!!

Here's the original post.....just for clarification!

Yep, saw that too - unfortunate wording, but obvious to me what the point is - the bullet starts below the line of sight, rises above the line of sight, then drops below. I'm sure his lack of precision in communicating his thoughts won't stop him from hitting his target.

This bothers me more - Assuming that the OP is implying that something about this statement is incorrect I shoot guns at a few local gun clubs and I have a range at my house and I always hear guys saying that bullets rise. I always just pretend that I didnt hear them and go on about my business.

David

quote:

I think discussing ballistics relative to line of bore is silly because most people are thinking in terms of line of sight.

The point of the whole issue at hand is not what "most people are thinking", largely because most people don't think and it often seems truth comes hard to them.

The point is, a bullet's drop is the same if fired or free and that's what the question tries to demonstrate. Meaning it's a physics question, not ballistics, and is poised to try to make non-thinkers understand there is no magic to bullets and they never rise above the line of departure/bore.

This thread is fascinating to watch, as all the experts argue over how a bullet drops to the earth.

I have no idea how that happens, I just find the topic interesting

quote:

Originally posted by Jim C. <><:

quote:

I think discussing ballistics relative to line of bore is silly because most people are thinking in terms of line of sight.

The point of the whole issue at hand is not what "most people are thinking", largely because most people don't think and it often seems truth comes hard to them.

The point is, a bullet's drop is the same if fired or free and that's what the question tries to demonstrate. Meaning it's a physics question, not ballistics, and is poised to try to make non-thinkers understand there is no magic to bullets and they never rise above the line of departure/bore.

Who cares about the line of bore? You can't see the line of bore, you can only see the line of sight. Exactly what relevant information are you gaining by describing the bullets path relative to the path of bore? How does that help anyone visualize what is happening with a projectile?

If you were standing on the ladder and it collapsed would you say you fell to the floor or would you say "no, no I didn't fall - my path relative to the initial path of departure never changed!"

When you are looking through your scope at a deer 400 yards away on the other side of a field, a tree with low hanging branches about 250 yards away directly between you and the deer are you visualizing the path of bore (an imaginary line extending off into space) and trying to calculate how far below path of bore your projectile will be? Or are you visualizing how far above the line of sight the bullet will pass?

Path of bore is largely irrelevant - in the field people see the line of sight and visualize the trajectory of the projectile, described in terms of rise or drop below the line of sight - probably why the military teaches it that way.

The whole discussion leads to a lot of erroneous information being printed that confuses people - I've seen gun writers write words to the effect that 'bullets begin to fall the instant they leave the barrel' - utter nonsense.

David

Someone heard what they think is BS. Certainly not on this forum.

quote:

I have no idea how that happens, I just find the topic interesting

It started giving me a headache about 15 posts in.

LWD

quote:

The Magnus effect can also be found in advanced external ballistics. Firstly, a spinning bullet in flight is often subject to a crosswind, which can be simplified as blowing either from the left or the right. In addition to this, even in completely calm air a bullet experiences a small sideways wind component due to its yawing motion. This yawing motion along the bullet's flight path means that the nose of the bullet is pointing in a slightly different direction from the direction in which the bullet is travelling. In other words, the bullet is "skidding" sideways at any given moment, and thus it experiences a small sideways wind component in addition to any crosswind component.[13]

Back in my attack helicopter days we called this the "port-startboard effect". When shooting to the right in forward flight, the relative wind hits the left side of the bullet and pushes it down (90 degrees later in rotation due to gyroscopic precession), when shooting to the left the opposite happens and the bullet hits high. With 150mph relative crosswind and 1000-1500m shots it is apparent.

The bullet will also drift to the right, again due to air friction and gyroscopic precession and the direction of rotation(causing the effect to be 90 degrees later in rotation) rather than producing lift. Again an extreme example, but can be seen at extremely long range.

Bob

quote:

Originally posted by Canazes9:

quote:

Originally posted by Jim C. <><:

quote:

I think discussing ballistics relative to line of bore is silly because most people are thinking in terms of line of sight.

The point of the whole issue at hand is not what "most people are thinking", largely because most people don't think and it often seems truth comes hard to them.

The point is, a bullet's drop is the same if fired or free and that's what the question tries to demonstrate. Meaning it's a physics question, not ballistics, and is poised to try to make non-thinkers understand there is no magic to bullets and they never rise above the line of departure/bore.

Who cares about the line of bore? You can't see the line of bore, you can only see the line of sight. Exactly what relevant information are you gaining by describing the bullets path relative to the path of bore? How does that help anyone visualize what is happening with a projectile?

If you were standing on the ladder and it collapsed would you say you fell to the floor or would you say "no, no I didn't fall - my path relative to the initial path of departure never changed!"

When you are looking through your scope at a deer 400 yards away on the other side of a field, a tree with low hanging branches about 250 yards away directly between you and the deer are you visualizing the path of bore (an imaginary line extending off into space) and trying to calculate how far below path of bore your projectile will be? Or are you visualizing how far above the line of sight the bullet will pass?

Path of bore is largely irrelevant - in the field people see the line of sight and visualize the trajectory of the projectile, described in terms of rise or drop below the line of sight - probably why the military teaches it that way.

The whole discussion leads to a lot of erroneous information being printed that confuses people - I've seen gun writers write words to the effect that 'bullets begin to fall the instant they leave the barrel' - utter nonsense.

David

Comparing projectile flight to line-of-sight is the final act of marksmanship .
the only things that affect line-of-sight is where you mount the "sighting instrument" and where you point it.

Line-of-sight is parameter independent of projectile physics.
The only link between the two is a tenuous mechanical one that creates an optical perspective.
( an important perspective, none-the-less in hunting considerations )
The projectile path is determined by where the barrel is pointing, not the "sighting instrument".

none of the physical variables of ballistics affect the line of sight , so its a risky context/perspective to directly relate the "field variables" to line-of-sight.

He He.......its not a case of the wind moving the line-of-sight ...........its a case of the wind moving the projectile path & adjusting the point-of-sight accordingly.

there are two perspectives to the sight picture hunters use ( target shooters typically use only one shooting for group & the good ones use a different one shooting for score).
- some hunters focus on the crosshair location on the target.
- some hunters have a more general picture which is the target itself with a crosshair relative to it.

there is a significant difference to these 2 concepts which might not be apparent to some.

Hunters that use the latter concept are the ones regarded as "naturals"..........they "feel" bullet impact location from a more general picture.

A similar situation exists in driving a vehicle.
- learner drivers focus on line of sight & wobble all over the road adjusting vehicle trajectory to their sight picture.
- experienced drivers "feel" vehicle trajectory from their inputs and have a more general sight picture

Drivers that use the first concept of sight picture see less of what is happening around them that can determine their fate & lose control of the vehicle when the vehicle trajectory is not in proportion to the steering wheel inputs on wet roads & gravel etc.

Drivers that use the second sight picture concept are placing themselves in the perspective of the vehicle trajectory of the moment & adjust additional inputs to modify the vehicle trajectory to that required at the time.

He He .......there are no F1 drivers, WRC drivers, or GP riders that use the first sight picture perspective.

Quote-
"Path of bore is largely irrelevant - in the field people see the line of sight and visualize the trajectory of the projectile, described in terms of rise or drop below the line of sight - probably why the military teaches it that way.

yep, teaching learner riflemen a basic simple average result methodology.

I guess that's why ( excluding snipers & advanced riflemen) the number of rounds expended in battle vastly exceeds the number of targets despatched........

The scale of the sight picture changes with long range hunting & accuracy is achieved by adjusting the crosshairs to the point of impact of the projectile under the external conditions existing at the time.
It is the line-of-sight that is adjusted to suit the variations in the projectile trajectory. Again, the "naturals" feel the inevitable variations in the conditions of the instant of launch and use the second sight picture perspective who are the most successful.

there are different contexts & perspectives, the human holding the trigger chooses a particular perspective to use.
That choice typically leads to the human's perspective of whether it is 'hunting' or 'shooting' in the field........and didn't that lead to some angst in the LR forum.

In the end it comes down to familiarising yourself with the weapon & load & choosing a perspective in your sight picture.

variations in context exist in the OP .
ie
bullet rise/fall relative to what.
The reader determines a context to the post content.That can be different to the post text & the text might not reflect the poster's intent clearly ( happens all the time in communication ).
None-the-less........the OP contains no reference to line-of-sight.
It does contain a reference to the bullet coming out. The projectile comes out of the bore of a barrel not a scope.
We are still left , as a reader, putting a context to the Marine Corps comment , as it does not provide a context other than that inferred by the OP text ( wherein there is only mention of the bullet coming out of the barrel).

The OP's second post clarified the question asked as relative to the bullet leaving the barrel.
At no subsequent post has the OP altered the context of his question to line-of-sight.

The vast majority of responses have remained within the context of the OP.

quote:

I've seen gun writers write words to the effect that 'bullets begin to fall the instant they leave the barrel' - utter nonsense.

David the writters you disparage are correct.

What you are so strongly concerned about is, as DenisB mentions, taken care of by zeroing the sights. Adjusting the sights properly requires an understanding what the bullets are actually doing.

I've never found ignorance of anything to be an advantage. IF a shooter has a flawed grasp of what's going on immediately after the bullet leaves the muzzle he will remain forever confused about the whole trajectory thing.

quote:

Originally posted by MickinColo:
This thread is fascinating to watch, as all the experts argue over how a bullet drops to the earth.

I have no idea how that happens, I just find the topic interesting

It's also great to see how many people have no problem identifying themselves as "clueless"!

Whenever I've calculated a trajectory it has always been from the drop calculated from a horizontal barrel.

Once the normal formula (Time of Flight^2 x 192.96) has been used to find the drop, the value is then corrected using Siacci's formula, or one similar.

Unless the drop distance is modified, the calculated trajectory will be excessively high - I've known people fire a dozen shots clear over the target at 1200 yards because they failed to modify the drop distance and used the classic School textbook formula.

quote:

Originally posted by Jim C. <><:


I once asked one of those guys what would happen if we fired the gun upside down. A dumb, vacant look for a few seconds, then a "light bulb" moment and a quick "The bullet will still rise." It' just magic, you know!

Such mental giants have no comprehension of the difference between 'line of sight' on a zeroed rifle and the 'line of bore/line of departure'. And you can't confuse many of them with facts either!

So, if you shoot the rifle upside down, does the bullet cross line of sight twice?