This came up as a friendly argument in hunting camp.

You have two rifle barrels, the same, except for chambers; one 7mm 08, the other 7mm STW.

We mount both barrels with the axis of the bore three feet off a perfectly flat floor a thousand yards long. There is no adjustment for trajectory. Accuracy is not the issue, or the object of the experiment.

Both barrels mounted in solid receivers with no chance of movement, up, down, or sideways.

Both rounds are loaded to max behind the same bullet; the 7mm 08 to 2800 FPS, and the 7mm STW to 3400 FPS.

Both barrels fire using one electronic trigger; they will fire at exactly the same nanosecond.

Two scenarios:

One, after we pull the trigger, which round will hit the floor first?

Second scenario; we adjust the firing so the 7mm STW fires late, so that both bullets leave the barrel at exactly the same nanosecond.

With this second scenario a delayed firing of the 7mm STW, which bullet will hit the ground first?

Gravity works! If you adjust the twist of both barrels such that they have the same rotational velocity to cancel out the precession (gyroscopic stabilization) of the projectile. And you had a way of varying the ballistic coefficient of the bullets in flight to cancel out the effect of changes in the BC due to velocity changes, then in the first case the STW would hit the ground first because it would leave the barrel first.

In the second instance the projectiles should hit the ground at the same time.

Interesting...
Barrels paralell to the floor;
In the second scenario, when both bullets leave the barrel at the same time and therefore graivty will be able to effect them at the same time, they will hit the ground at the same time.

The only difference is that the STW will land further down the range.

Following this logic, I beleive that the STW would hit the ground first in the first scenario because gravity will act on it sooner, because it will leave the barrel first.

I'm sure someone will present the proper equations. But thats my thoughts, I think,

BigBullet

The physics are simpler than you think.

For all practical purposes, a bullet fired horizontally will hit the ground at exactly the same time as a bullet dropped from muzzle height at the same instant, regardless of muzzle speed. The downward acceleration is independent of the forward motion.

It's even better than that. If you aim a tube upward at 45 degrees, at an object, and shoot a projectile at the object, and arrange things so that the object begins dropping at the same instant the projectile leaves the barrel, both the projectile and the object will accelerate downward at the same rate, and the projectile will strike the object. We used to do that demo when I was assisting with Physics 100, a millenium or so ago.

There is one slight deviation from the above: Bullets in flight do experience a slight amount of aerodymanic lift after they pass their peak elevation. In a vacuum, the model is perfect. With slow projectiles, it is awfully dang close. With fast projectiles, it is just a trifle off, but not much.

quote:

Originally posted by RogerK:
This came up as a friendly argument in hunting camp.

You have two rifle barrels, the same, except for chambers; one 7mm 08, the other 7mm STW.

We mount both barrels with the axis of the bore three feet off a perfectly flat floor a thousand yards long. There is no adjustment for trajectory. Accuracy is not the issue, or the object of the experiment.

Both barrels mounted in solid receivers with no chance of movement, up, down, or sideways.

Both rounds are loaded to max behind the same bullet; the 7mm 08 to 2800 FPS, and the 7mm STW to 3400 FPS.

Both barrels fire using one electronic trigger; they will fire at exactly the same nanosecond.

Two scenarios:

One, after we pull the trigger, which round will hit the floor first?

Second scenario; we adjust the firing so the 7mm STW fires late, so that both bullets leave the barrel at exactly the same nanosecond.

With this second scenario a delayed firing of the 7mm STW, which bullet will hit the ground first?

In a vacuum if the bullets leave the barrel at the same instant, they will drop freely at the same accelerated rate and will hit at the same instant. So the answer to your 2 scenarios is that if gravity acts at the same instant, then they will drop precisely the same in the vertical dimension.

I truly don't know if there are any effects that might be generated by rotation alone (can't imagine) or rotation effects generated on the atmosphere/bullet surface interface. These could possibly modify things slightly.

Then, of course, there are the relativistic effects: if you're standing at the barrels, the bullet from the slower projectile will appear to you to hit first under special relativity (as the light from the hit will arrive at your location prior to the light from the more distant "simultaneous" hit). I guess the faster projectile would also have a slower clock, and that would mean that it's 't' would actually be less than the slower bullet's 't' by a minisucle , but computable, amount.

I am no physicist, I don't know if these 2 relativistic effects would act additively or ar part and parcel.

Yes, time dilation will happen. The effect will be roughly s/c, where s is the speed of the projectile, and c is the speed of light. That's about (3000 f/s)/(186,000 miles/sec x 5280 feet/mile). Not a first order effect...

quote:

Originally posted by denton:
Yes, time dilation will happen. The effect will be roughly s/c, where s is the speed of the projectile, and c is the speed of light. That's about (3000 f/s)/(186,000 miles/sec x 5280 feet/mile). Not a first order effect...

Hey...

While I'm no physicist, I can calculate what you gave me above: 3 and a smidgeon times 10^-6 is worth hours of argument wouldn't you say!!!

quote:

Originally posted by denton:
Yes, time dilation will happen. The effect will be roughly s/c, where s is the speed of the projectile, and c is the speed of light. That's about (3000 f/s)/(186,000 miles/sec x 5280 feet/mile). Not a first order effect...

Just thought of another effect: the faster bullet will have farther to fall due to the earth's curvature as well unless the range is specially constructed (seems to me I read about this in Sci Am as being important in those lasers that are built for those gravity wave detectors--LIGO or some such?).

Time of flight is also why the old myth of "hold only for the horizontal distance when firing up/downhill" is wrong.

If horizontal distance were the only thing that affected bullet drop, then two bullets fired in two different temeperatures would hit the ground at the same point (given the assumptions in the above hypothetical).

Hello the campfire!
What a question! The physical theory is that the two would break the same plane at the same time. Acceleration and velocity would have no affect on the flight time. The critical issue is having the barrels parallel to the ground plane. A bullet in flight will not rise above the plane of the barrel, so the actual distance of flight will not be as far as you might think. The so called trajectory is introduced by raising muzzel to cause a longer flight distance.
This assumes, of course that the bullet does not reach escape velocity and enter near earth orbit.
Judge Sharpe an poor widows son.

quote:

Time of flight is also why the old myth of "hold only for the horizontal distance when firing up/downhill" is wrong.

Are you saying that "hold over/ bullet drop" is the same at any 400 yard range regardless of the angle of the shot. If the shot is 400 yards straight up there is no "hold over". If that is the case, then there must be some validity that gravity acts only on the horizontal distance. For instance, if I am shooting at a target 400 yards away, but 45 degrees uphill, then the actual "gravity distance" will only be 283 yards. This is simple geometry and physics (A squared + B squared = C squared). Time in flight is just how fast the bullet gets there.

Got interested, pulled out my MathCad program, and calculated the Newtonian results in a vacuum.

Answers are that if triggers are pulled simultaneously the 2800 fps bullet hits 404 yards downrange 0.43444 sec later and the 3400 fps bullet hits 491 yards downrange 0.43419 sec later. If the triggers are offset so that time zero is when both bullets simultaneously leave the barrels, then they both hit 0.43301 sec later at the same ranges downrange, of course.

Full analysis is available at: bullet.pdf

quote:

Originally posted by GA DEER HUNTER:

quote:

Time of flight is also why the old myth of "hold only for the horizontal distance when firing up/downhill" is wrong.

Are you saying that "hold over/ bullet drop" is the same at any 400 yard range regardless of the angle of the shot. If the shot is 400 yards straight up there is no "hold over".

Yes there is a holdover. Think about it. If you shoot straight up and your sights are, say, 1" above the barrel, your shot will be precisely 1" "below" the aim point (i.e., 1" in the direction of the bottom of the gun) for all altitudes the bullet can reach.

Check out this web site. It explains it much better than I can.

http://www.loadammo.com/Topics/April04.htm

Denton,

Wouldn't it rather be the difference in time represented by the speed of light over the distance between the bullets when they strike the ground?

If the distance above the ground when fired is D, then the time, T, to stike the ground (in a vacuum) is from D= (1/2)AT^2 for acceleration A (32.17 ft/s^2).

Then the lag in time would be the difference in bullet velocities, (DV), times T divided by the speed of light.

T(DV)/(186,000 miles/sec x 5280 feet/mile).

Right? Still not a first order effect!

quote:

Originally posted by Will:
Denton,

Wouldn't it rather be the difference in time represented by the speed of light over the distance between the bullets when they strike the ground?

If the distance above the ground when fired is D, then the time, T, to stike the ground (in a vacuum) is from D= (1/2)AT^2 for acceleration A (32.17 ft/s^2).

Then the lag in time would be the difference in bullet velocities, (DV), times T divided by the speed of light.

T(DV)/(186,000 miles/sec x 5280 feet/mile).

Right? Still not a first order effect!

Calculating the separation at the time they hit at 259.8 ft, I get the differences to come out in the 7th place. That is, an observer at the barrels will measure the slow bullet to hit at 0.4330139 sec after leaving the barrel while measuring the fast bullet to hit 0.0000003 sec (3*10^-7 sec / 0.3 microseconds) later at 0.4330142 sec. This is very easily within the range of modern timemeasuring technology!

Re. calc: the order of magnitude of where relativity effect is impt is, I think, correct. [check of solution: lightspeed =~ 1 ft/nanosecond, 259 ft would add ~ 300 nanoseconds to account for lightspeed differences in reporting hits] But I certainly did not carry significant digits through with enough care to say the result is actually accurate to 7 places.)

If it's timed that both bullets leave the barrel at the same time as in the 2nd example they will hit the ground at the same time.

In the first example where the 7mm STW bullet will leave the barrel first, its bullet will hit the floor first but will travel farther.

It's a matter of the amount of time gravity has to act on each bullet.

quote:

Calculating the separation at the time they hit at 259.8 ft, I get the differences to come out in the 7th place. That is, an observer at the barrels will measure the slow bullet to hit at 0.4330139 sec after leaving the barrel while measuring the fast bullet to hit 0.0000003 sec (3*10^-7 sec / 0.3 microseconds) later at 0.4330142 sec. This is very easily within the range of modern timemeasuring technology!

Re. calc: the order of magnitude of where relativity effect is impt is, I think, correct. [check of solution: lightspeed =~ 1 ft/nanosecond, 259 ft would add ~ 300 nanoseconds to account for lightspeed differences in reporting hits] But I certainly did not carry significant digits through with enough care to say the result is actually accurate to 7 places.)

Owww! You're making my head hurt!

Trivia question:

Who was the American astronaut who tested this very same theory on the moon by dropping a bowling ball and a feather?

Anyway, a couple of you guys nailed it...if the bullets leave the barrel at the same time they hit the ground at the same time...in a vacuum. One other factor...objects in relative motion in a fluid experience a suction between them. This force is proportional to the velocity difference, so the STW will be 'sucked' to the curface slightly ahead of the 7-08.

Isn't physics fun!?!?!?

quote:

Originally posted by CDH:
Trivia question:

Who was the American astronaut who tested this very same theory on the moon by dropping a bowling ball and a feather? <snip>
Isn't physics fun!?!?!?

I won't give away the answer, but it was a feather vs. hammer not a bowling ball..

Gallileo would have liked to see this done with a bowling ball (more similar to his canonball!), but I'm sure he would have been satisified with the hammer vs. the feather in the vacuum of the moon.

And a final phrase for any history buffs: E pur si muove...

jpb

quote:

There is one slight deviation from the above: Bullets in flight do experience a slight amount of aerodymanic lift after they pass their peak elevation.

Other than in a model vacuum environment the time of flight will be affected by Angle of attack(Alpha) as implied by Denton's post. Higher gyroscopic stability(SG) resists tractability(SG and tractability are inversely proportional) and thus increases Alpha, which increases aerodynamic lift. As Denton indicated it is a very small factor, but if all else is equal the bullet with the higher SG will strike last.

Further discussion on the subject can be found in Robert McCoy's book "Modern Exterior Ballistics" among others.

In a previous post, someone mentioned the term "aerodynamic lift." I'm not sure I can buy that theory. It is my understanding that the reason planes have lift is because of speed and the fact that their wings tilt, causing wind resistance, thereby creating lift. I haven't read any evidence showing that a bullet can defy gravity and lift once fired. If that were the case, how would you compensate for this lift when you are shooting? Someone enlighten me please.

murftj,

It's not a theory dude, go read the book I referenced. McCoy was a little bit more than a weekend ballistic tweedler.

You may find further illumination in "Rifle Accruacy" Facts by Harold Vaughn, or "Understanding Firearm Ballistics" by Robert Rinker.

BTW, your understanding of why airplanes fly is incorrect. It has NOTHING to do with "resistance" or "tilting" wings. Do a google on aerodynamic lift...

You might even learn something from this too:
http://www.nennstiel-ruprecht.de/bullfly/index.htm#Formulas

There are at least a couple of people on the board that have probably read more about this than I have. But since I brought it up, as nearly as I can figure out the lift works like this:

The axis of the bullet does not stay in the same orientation as when it left the muzzle. If the wind is blowing, the bullet will nose into the wind, and past the peak of the trajectory, the bullet will nose down. It isn't much, probably a fraction of a degree.

Besides gravity, the other external force on the bullet is drag. Drag is a vector that points straight out the tail of the bullet. But the tail of the bullet is slightly tilted up, so the drag vector has both a horizontal component, and a vertical component, i.e., lift.

So, if I got it wrong, somebody help me out. But I think that's how it is, having read Vaughn on wind drift. As Dan stated, this depends heavily on SG.

I am amazed and pleased at this discussion. I have been a mathematician and information technology professional for 40 years. In the field of firearms I seldom hear a factual discussion of internal or external ballistics, and less seldom see one in popular magazines. So much of firearms mythology is based on bullshit that I generally keep my mouth shut during conversations about guns and physics. I want to stand up and applaud you guys for your interest in the reality of firearms! It would be great if you could take this
particular interest in physics and request, no, demand that your favorite gun writer get educated and quit
spreading malarky.

Appreciatively submitted,

OEH

Denton, that is essentially correct, except that normal bullet orientation is tail down or nose up depending on perspective. Right hand twist will cause a slight offset of bullet axis to the right regardless of wind, LH twist will do the opposite. This causes "spin drift". The reason for positive Alpha is found within the framework of tractability. Bullets "nose over" during their flight and remain oriented to flight path rather than bore centerline. However, this is the resultant of forces(aerodynamic, gyroscopic, and gravity(sigma)) acting on the bullet, and thus it always lags very slighly behind flight path, hence the positive Alpha which generates small amounts of lift. It is not the result of Magnus force as some believe.

As I stated earlier Tractability is inverse to SG, and higher values of SG will compound this as well as spin drift. I have read info that seems conflicting to me at this point in regards to the ultimate end game of the tractability/SG in extreme scenarios. One side holds that in exteme circumstance it can lead to stability upset due to aerodynamic loads, the other side says 'No'. I suspect both sides are right, the active agent being bullet design and materials, or the difference betwist CG and CP.

It is easy to look at these issues with a focus that leads astray because of tunnel vision. The issues I speak of above are but a very few of the factors acting on a bullet in flight and I will not try to examine it all in one post. You may believe, or read as you see fit. Me, I probably have some Missouri influence in the family tree, so I read a lot. A few years back I was blissfully ignorant of the three disciplines of ballistics, then one day I decided to learn all about it. Now I understand why people specialize, and my wife appreciates that I eschew an indepth study of the other two. McCoy made me babble a lot in my sleep.

That said, you(Denton) know more about Internal ballistics than I do about Exterior ballistics, so I don't charge for my "help". Hope it's worth more than that.

For the lift proponents...are you referring to the slight angle between the bullet axis and the flight path?

Isn't it all relative? IOW, isn't the relative bearing/axis of the bullet to the flight path the critical factor? If so, how can we assume that the bullet is slightly canted nose-up? It leaves the bore with a tiny bit of wobble (Sierra calles it 'coning motion' or something like that)...and it stabilizes/damps out pretty soon....but that should be of a much higher order of magnitude...for the first hundreds of yards at least.

CDH...

At least in my case, that's what I'm referring to.

The bullet "coning" is a separate issue.

The bullet will try to assume an orientation of minimum drag. If the wind is blowing, it will nose into the wind, because that is the lowest net drag position. Vaughn calculates this as about .5 degree off axis, for a 20 mph wind. You now have a drag vector pointing out the tail of the bullet with a large backward component, and a small transverse component. It is this transverse component, NOT the wind blowing against the side of the bullet, that is the main actor in wind drift.

Since bullets are normally fired upward at a slight angle, during the first part of their trajectory, the nose is slightly up, so the drag vector points backward and slightly downward, giving negative lift. After the peak of the trajectory the situation is reversed, and the nose is down, creating a slight upward component. A small amount of forward motion is cannibalized to create a small upward force.

My mind was locked into the true horizontal firing model in the question originally asked, so I ignored the downward component during the first part of the trajectory, which Dan correctly reminded us of.

Added later: Think of a bullet fired straight down from a helicopter, hovering. The drag vector points straight out the tail of the bullet, directly upward. The bullet descends more slowly than it would in a vacuum. That's lift.

I think you are groping now, as I do not see how drag becoems lift. I do not see how a bullet would nose into the wind because of less resistance, as blowing off course from the wind (with the wind) would be less resistive.

A 40 mph wind from the left and the bullet points to the left? I ain't buying that!!

Will, (DD and Denton, correct me if I have this wrong) let me see if I understand the theory...

The bullet will always point in the 'relative' direction of the wind resistance. Obviously, the vast majority of that resistance at normal velocities is in the direction the rifle is shot.

In a crosswind, there is a small component of the 'net' wind the bullet 'feels' that is sideways (are you familiar with vector analysis...???) and the aerodynamics of the bullet will cause it to 'turn into the wind'.

Simple, right? I am not sure how much the bullet spin will resist this turn (it must to some degree, that's why we spin them with the rifling) as well as resist the turn due to the bullet arcing through the air as previously mentioned...but that is my mental issue to work through.

Same concept...ever watch American style Football? Next time you see a perfect punt or a 'hail mary' pass with a perfect spiral, watch how the nose of the ball goes from angled up during the rise to down during the fall. Same effect...I think...just not sure how much the magnitude applies to bullets at MUCH higher relative velocities and spins...I know, clear as mud!

DD, Denton...if a Left to Right crosswind causes the impact point to shift to the right (as we know it does from shooting it)...

...AND the same L>R wind causes the bullet nose to point to the L

...AND the 'lift' theory would cause a nose left bullet to stray L

...should we then conclude that the lift from the bullet angling (wind and/or trajectory) is VERY small???

The lift is, indeed, small. It is a downward force before the peak of the trajectory, and an upward force (lift) after the peak.

Yes, the bullet points into the wind. Thought experiment: You suspend a bullet on frictionless swivels, in the middle of a taut string. Then you set up a blower, moving air over the bullet. Just like a weathervane, it will turn into the wind. In flight, the bullet will turn so the net airflow (vector sum of crosswind and apparent air motion due to bullet travel) passes directly from point to tail.

The drag vector is now no longer parallel with the trajectory, and has a component in the direction the wind is blowing. That, not the wind blowing on the side of the bullet is the main actor in moving the bullet in the direction of the wind.

And if you figure out how gyroscopic action fits into the lift thing, please explain it to the rest of us!

quote:

Originally posted by GA DEER HUNTER:

quote:

Time of flight is also why the old myth of "hold only for the horizontal distance when firing up/downhill" is wrong.

Are you saying that "hold over/ bullet drop" is the same at any 400 yard range regardless of the angle of the shot. If the shot is 400 yards straight up there is no "hold over". If that is the case, then there must be some validity that gravity acts only on the horizontal distance. For instance, if I am shooting at a target 400 yards away, but 45 degrees uphill, then the actual "gravity distance" will only be 283 yards. This is simple geometry and physics (A squared + B squared = C squared). Time in flight is just how fast the bullet gets there.

No, time of flight dictates how much a bullet drops. A bullet will drop more at 400 at a 45 degree angle than at 283 yards. The time of flight is longer, and it will drop more. It won't drop as far as a 400 yard target over level terrain, but it will drop more than the 283 yards. It will also drop slightly less going downhill than uphill, since gravity "pulls" the bullet down and thus decreases the time of flight slightly.

If you have RCBS.Load, see for yourself. Many cheap applications correct for angles by calculating the horizontal distance thing.

Guys, I am resisiting with all my earnest might that possibility that I'm being drawn into a never ending thread!

The first thing anybody has to accept that in the world of exterior ballistics, it ain't simple. Next thing is, do you really want to know all that crap so's you can ponder it while your bullet wanders downrange? Well, given that you're chatting about it I'm going to try to embellish a little of what I said earlier by stating what is happening to your bullet, even if I don't explain why in each case.

NO WIND, NO BULLET IMBALANCE

Given that there are three lines of interest in the discussion I shall label them. Bore axis, line of sight and bullet path. Given a perfect world the last two will intersect at a point close and far from the muzzle, though the bore axis, or center, intersects with the others only once near the muzzle, assuming the rifle is sighted in a normal fashion.

When a bullet exits the muzzle it begins to drop immediately from the bore axis, and if your perspective was from that reference the bullet would soon be lost to your sight. This is true regardless of the orientation of LOS and trajectory. The barrel may well be level and parallel to the earth's surface, or not, it matters not.

Gravity acts on the bullet as a force downward, its influence immediate upon departure from the muzzle. Because it is a force and not magic, it causes the onset of precession of the bullet in the form of a wobble, or nutation, much as a top wobbles when it is first released. The results of this is that the bullet will have a very slight cant or offset, to the right with RH twist, and to the left with LH twist barrels. Precession acts at right angles to the applied force and axis of rotation, in the direction of rotation. This offset is extremely small, on the order of tenths of a degree or even less in some cases. It is directly proportional to SG and is NOT caused by aerodynamic forces in the flowfield. It causes the bullet to deflect off course according to twist direction, and if I recall correctly, it can amount to something in the order of 6" at 1000 yards for the average BR rifle.

The Lift generated by the flowfield around the bullet is a result of tractability, that being the characteristic of gyroscopically stabilized bodies to remain oriented to the flight path. Because that path is curved here on Earth it necessarily follows that the pitch of the bullet is constantly changing, just at previously mentioned in regards to the football spiral. It LAGS behind the actual path, or trajectory very slightly, and because of this it has a very small positive Alpha, or angle of attack. This generates lift, albeit a very small amount. It will delay the bullets contact with planet Earth very slightly.

So, now we got us a RH twist barrel that just spat a bullet of some form downrange, and it is cockeyed, nose high and right. This is where is gets a little screwy.

CROSS WIND, AND BULLET NOT BALANCED

In the real world there is always a cross wind. And bullets are never precisely balanced. Enter Mr. Murphy.

Bullets can be and are out of balance in several ways. Firstly they are not balanced about the central or designed axis, and secondly there are longitudinal variations of weight distribution that cause slight differences that deviate from the intended CG. The barrel will keep a bullet rotating about its designed axis, but as it leaves the barrel it will begin to transition to rotation about the center of balance on the axis of rotation. The event is referred to as Projectile Jump. Differences in fore and aft imbalance will confound this issue somewhat, and when all is said and done it is certain that your bullet will be precessing in a epicyclic mode(dual, fast and slow), or a rosette pattern if you could allow the bullet nose to mark a pattern on paper. It is also likely that your bullet will actually have a tricyclic precession(three modes), and if you want to graph that one, pull out your Cray Computer and have a great day!

The slow cycle precession will grow larger or smaller as a function of SG as the bullet traverses downrange, it will NOT null at any point in the bullet's travel. The fast cycle precession caused by imbalance about the longitudinal axis will null within 200 yards or less. Imbalances fore or aft of CG have their own characteristics and I'm not certain they are terribly significant in regards this conversation. I couldn't really begin to explain them anyway.

Wind causes a number of effects on bullets, Drift being the most commonly discussed. It really isn't drift, it's a deflection. See the other post in this forum regarding my comments on "drift". Denton is correct that conical proectiles will cant into the wind, this being the path of least resistance. It occurs through the process of precession.

Wind also causes aerodynamic jump. A cross wind, R-L will cause a bullet from a RH twist barrel to shoot high, or low if the wind is from the left. Reverse the twist, reverse the effect. It has to do with the effect of the flowfield on the bullet, as translated by SG.

All of these issues are related to gyroscopic stability for the most part, and in the course of a bullet's flight there is a constant evolution of calculus, and a neverending resultant, or average, in all of these forces and the upsets they cause in the bullet's stability. I am sorry to inform you that your bullets never travel a straight and true path. They always wobble and jiggle, and who knows what else, mostly because nothing is truly perfect, and we have made our bed with gyroscopic stability. In actual fact your bullets follow a path that resembles a helix, thought that is not the proper term. That they can on occasion make bug holes on paper, means that it is both a very small helix, and if you are successful, very consistant. Now you know why BR shooters are an anal retentive lot.

So, how do people know this? The technology for observing what bullets do in flight has been around for a long long time. Over the years it has evolved into two primary modes of observation. One is Spark Shadowgraph Photography(pictures) and the other is Millimeter Wave Length Radar, a technology that renders images so clear that rifling marks are visable on bullets over the entire length of their travel, so too are the wobbles and such. These things have been observed and measured, and such activity continues at the Aberdeen and Sandia Labs, and doubtless a number of military facilities as well. These are the places McCoy and Vaughn worked at, and they are the fathers of modern aeroballistics. Being that they were real genuine rocket scientists and all, I have faith in their words.

I hope this helps somebody, somewhere, somehow. If not, go buy the books I mentioned above and find a very quiet place to read, and THINK.

Thanks Dan, where's the Tylenol?

Dunno fella, but sour mash is a reasonable substitute.

Nice post, Dan. Very helpful.