It seems that some shooters believe in the theory that certain loads can actually defy the laws of physics and shoot much tighter groups at longer ranges(IE 1.5 MOA at 100 and .5MOA at longer ranges).

I personally feel it has always been a myth, but I hear it brought up at the range from time to time.

This totally goes against what I learned in engineering school and my experience at the range. I've shot thousands of rounds and been around countless others and I have never seen a rifle shoot better at longer ranges than it did at mid range on a consistent basis. If they did, it was a fluke. The best shooting target rifles I've seen shot nice groups at long range and itty bitty groups at short range.

Curious what you all believe?



Have a Good One,

Reloader

I would be curious also how for example you shoot .5 inch group at 100 and a 1 inch group at 300. How is that possible, or at least consistantly possible.

I have heard about this all my life but I have never seen it.
Ken

Well the story was as I understand it is that some bullets gyrate/wobble on leaving the muzzle
possiblely from going from centre of bore to centre of the bullets gravity, and effect of excaping gasses on the base of the bullet on exit.
Presumably they are still wonky at 100yards but "go to sleep" for the longer ranges.

I tend to sit on the fence which is why I have a sore a**e.

OK, if a rifle shoots consistently better at 300 than at 100, then you'd be able to take that rifle, and shoot through an imaginary target at 100 with a wide (angular) group, and then somehow those bullets not only stop wobbling (which maybe I could believe), but actually start correcting for the angular error that they had in the first 100 yards? In other words, if a bullet started out 0.5" left at 100 yards, it is on a path to be 1.5" left at 300. How would a bullet that was left at 100 know to correct to the right after 100 to close the group at 300?

It doesn't.

Andy

My Kimber 8400 300wsm consistently shoots one inch groups at 100 yds and 1 inch groups at 200yds (1moa and .5moa). I'm not trying to start an argument, I'm just as confused as the rest of you

Don't confuse improved accuracy( putting a number of bullets in or close to the same hole) with point of impact.
If the bullet is still gyroscopicly (?) unstable at 100 yards it could have the point of impact rotate,say for conversation purposes, and give a grouping of 1 inch.
Once,if, the projectile settles into stable flight-especially if it enters subsonic territory where there is little to no burble caused by air displacement at the speed of sound velocities- the bullets will tend to impact into a closed grouping-this says nothing about WHERE on the target they will impact just that they will be closer together,hence, "improved" accuracy.
To get the desired results you will have to adjust the sights/scope to account for this new POI.
Watch a high speed video of either a bullet or jet going through the sound barrier to better understand the tremendous turbulence achieved at that time.

Hope this helps.

Gary

I don't think the sound barrier applies here unless you are shooting a low velocity round.

If a bullet is unstable from it's starting point, but stabilizes in flight, it will continue upon the angle at the point of stabilization only effected by forces such as wind, air density, gravity, etc etc. Bullets do not magically correct themselves as some believe.

Reloader

quote:

This totally goes against what I learned in engineering school and my experience at the range. I've shot thousands of rounds and been around countless others and I have never seen a rifle shoot better at longer ranges than it did at mid range on a consistent basis. If they did, it was a fluke. The best shooting target rifles I've seen shot nice groups at long range and itty bitty groups at short range.

I started a thread on this very subject many months ago. No one came up with any convincing theorey about how divergent bullets could somehow regroup and then come together again. There is no principle in physics I know of that would allow that. The most logical explanation I heard was that if the scope parallax was improperly adjusted, a rifle might group better at a longer distance than at a shorter one.

Grumulkin,

I've also thought parrallax could be a cause.

Have a Good One,

Reloader

in the 2008 gun digest there is an article on the krag that addresses the issue pretty well

quote:

My Kimber 8400 300wsm consistently shoots one inch groups at 100 yds and 1 inch groups at 200yds (1moa and .5moa). I'm not trying to start an argument, I'm just as confused as the rest of you

All bullets yaw during flight. (Some a lot). This causes them to 'fly' in a spiralling path around the mean flight path. In this case, the spiral has a mean deviation from flight path of 1/2 inch. Usually, the mean deviation increases with range. Sometimes it dampens down as the yaw decreases. The SMLE was known for this in target shooting. (I don't know about the No.4 ). This has actually been proven but I can't tell you were to find the details right now. There is a website that covers the subject. Doppler radar has been used to trace bullet velocity over a long range and it was found that at the extreme ranges, bullets were slowing then speeding up! Well, they weren't actually doing that. The velocity was been measured from an angle at the end of their trajectory, and the spiralling bullet path gave that effect.

Remember that wind affects a bullet's path hugely. Just look at the rate a bullet slows in flight. Airflow forces on it are 'massive'. As the bullet yaws, it presents a slightly different angle of attack, which has the same effect as a crosswind. The yaw is not at the same rate as the bullet spin but is constant. This causes it to spiral.

Pure BS, period. When some "expert" at the range spouts off about gyros and angular momentum or some such facade of sophistication, just smile and nod.

I find myself laughing here in front of the computer. What would you do with such a rifle while hunting? First, spot your quarry at 20 paces, then stalk backwards to 200 yards???

Hunter A: "How'd ya miss em?"
Hunter B: [shakes head] "Too close I reckon."
Hunter A: "Damn."

quote:

Pure BS, period. When some "expert" at the range spouts off about gyros and angular momentum or some such facade of sophistication, just smile and nod.

Well, yes and no. You are not going to measure or see the effects at the range. Not unless you have an unusual rifle and load combination, as David Antonucci does. (Or your ranges are very long, as in Bisley type shooting. Then you have to contend with wind which will disguise the effects. And shooter error plus rifle/load error - even the sun heating one side of the barrel).

303Guy,

I find the information you present to be very interesting. The phenomenon you describe is absolutely possible, paper airplanes do it all the time!

If this phenomenon is actually occurring in some instances, it would mean that the "group" size is potentially growing and shrinking in a periodic fashion as the bullet travels downrange. We could regard a paper target as a "snapshot" of the state of affairs at a given range.

What I callously regarded as "Pure BS" is an improvement in the spread of the mean flight paths of a group of projectiles as the range increases. That would be incredibly unlikely. This spread is zero at the muzzle. For a set of 3 or 5 or 10 projectiles to have mean flight paths that diverge, differently I might add, from the bore axis only to converge downrage....yikes.

303,

The problem is the spiral flight path is nearly impossible to replicate. Shall this be replicated through a series of groups, pure luck.

Like I said, physics just doesn't prove this can happen. I personally have never seen someone prove this theory, although it would be nice to see this proven by a series of say 10-10 shot groups at say 100 and 500 yards to back this theory. I just don't see it happening. Of course it would have to be in a vacuum with a machine rest etc...

I think another member is onto something with the paralax theory.

Have a Good One,

Reloader

I, for one, am not on the parallax bandwagon. It seems that parallax holds a strange distinction in the minds of shooters. I won't criticize those who think parallax is at work here, as I haven't looked at that angle thoroughly. I will note, however, that parallax seems to get the blame for all manner of shooting phenomenon.

In other words, parallax seems like some sort of Bermuda Triangle to many. Parallax didn't cause the extinction of the dinosaurs and parallax didn't kill Kennedy from the grassy knoll either.

Really, parallax is simple business. Check out the Wikipedia article, I'll be educating myself there too.

Hey Reloader, I believe it is a number of things, including Parallax.

First off, I don't believe it will happen with "every" group shot at the longer distance. But it happens often enough that something is going on.

It could be as simple as the actual Target. Perhaps you have heard the old saying, "Aim small, hit small!" Most folks seem to use the exact same Targets at long distances that they use up close. That in turn forces them to be more precise when aiming when the Target looks smaller at distance. This is a separate issue from Parallax.

And I rarely see people practicing at long distance and being in a hurry. Some of the folks shooting at 100yds or closer seem to simply be practicing how fast they can get a series of shots off. I've no problem with that, but it certainly does not enhance accuracy.

I also find people shooting at long distance are typically using a Scope with more power than 4-6x. I can't say for sure, but I doubt a person using a 4-6x Scope will find they have smaller groups way out yonder.

Probably others if I had a bit more time, but that should be good for fodder.

quote:

Originally posted by 303Guy:

All bullets yaw during flight. (Some a lot). This causes them to 'fly' in a spiralling path around the mean flight path. In this case, the spiral has a mean deviation from flight path of 1/2 inch. Usually, the mean deviation increases with range. Sometimes it dampens down as the yaw decreases.

Hey 303, this is my "theory in progress". I haven't gotten any smaller groups at longer ranges but I have seen anecdotal evidence of the bullet groups moving from side to side. In other words, the group might be dead center at 100 yards, to the right at 200 yards and to the left at 300 yards. This is hard to document and state as fact because any wind has a profound effect at the longer ranges.

Correct me if I am wrong, but in tuning a bow and arrow, you shoot through a piece of paper positioned at a close distance and look for the keyholing effect of the rear of the arrow going from side to side. After this yawing at a close distance the arrow stabilizes and flies with the arrow body in line to the target. The analogy fails when you factor in the immense stabilizing effect of the fletching which bullets do not have. However there could be some of this on a much smaller scale with bullets.

Just rambling, much like Hot Core (except he's better at it )

quote:

Originally posted by BigJakeJ1s:
(which maybe I could believe), but actually start correcting for the angular error that they had in the first 100 yards?
It doesn't.

Andy

The diagrams I have seen, probably on AR maybe a year ago, posted by someone, suggested that the bullets were leaving the barrel doing a cork-screw motion through the air.
So it would depend where in that arc they happened to hit at close range.

When that cork-screw motion stopped the bullet was supposed to return to the centre path in diminishing diameter corkscrews so to speak.
It probably is only noticable with some rifles and some bullets.

I'm still straddling the fence on this.

I know what you mean on the targets and time HC, good point.

The problem I have with the cork screw theory is the fact that every bullet would have to stabilize at the exact point and be exactly in the center path upon stabilizing, not going to happen IMO.

The whole point in building accurate loads is having them stabilized from the start.

Have a Good One,

Reloader

I believe that bullets fired from my rifles execute two basic motions when in flight.

Precession which is the slow corkscrew motion of the bullet and superimposed on this is nutation which is a fast rotating motion.

The nutation motion damps out over distance, between 60 or 100 m whilst the precession motion remains, that precession motion however changes over distance as well but not as pronounced as the nutation motion . The motion dimension as expressed in Pitch and yaw is small @ 200 m but then gets slightly bigger @ 600 to 1000m.

This is directly related to angle of attack. ie the angle of the long axis of the bullet relative to the direction of flight, this can actually be observed on the target. If I look carefully using a magnifying glass at the smear pattern of the bullet holes on a paper target one can see what bullet has the most angle of attack, typically Berger or other precision made bullets cut a very small hole with very even smear pattern around the hole.

Angle of attack changes over distance, because Angle of attack is equal to the square root of the sum of yaw and pitch and yaw and pitch are not equal at all points on the trajectory

But then I can only speak for my rifles and my opinion ?

The second and more important issue is barrel harmonics, again I can speak to my rifles and opinion only, this is likely the reason why certain loads do well over distance and others not, because sometimes i'm "lucky" and strike a load that creates a "harmonics match" that gives best accuracy.

So with this in mind I, again my opinion only would load to harmonize with a particular barrel. This for me is not so much at issue with plain hunting rifles but does become an issue @ 1000 m

458_wanderer, For what my opinion is worth, I think you summed it pretty well. It does seem to happen often enough to be noticed. Meaning that occasionally a rifle/load combo is accurate enough for the spiralling mean flight path of each bullet to be the same as the next. (I never thought about the

Here is a good read on the subject(external balistics). It is a bit long but full of info.
It explains some of the events being discussed.

http://www.nennstiel-ruprecht.de/bullfly/index.htm#Figures

muck

My experience is of the practical variety, not scientific. To say that this is impossible or BS is wrong. I have seen it numerous times, and quite consistently. I have rifles that are .5 MOA at 100 and .5 MOA at 300, some that are 1MOA at 100 and 1.5 MOA at 300, and some that are 1MOA at 100 and .5 MOA at 300. Can't tell you why, but it does happen, and pretty much any match shooter will agree. There are any number of match shooters who can prove this with a a super accurate rifle and shooter. I have a .338 WM that is this way, consistently 3/4 in at 100 and 200 yards. I realize geometrically it doesn't make much sense, but there are some things at work here that I don't understand, but that doesn't mean it is BS. It happens, talk to some long range match shooters.

OK ALF, now I have a headache! Would you mind saying that a bit slower?

OK, this 'nutation', is that the motion which is kinda slightly like a propellor motion? The wobble of the rotational axis so to speak? I'm thinking the bullet has four motions; forward motion, spin about it's longitudinal axis, a longitudinal axis offset spin (which I am refering to as yaw?) and a spiralling motion about it's mean flight path. (And maybe even a crooked mean flight path). Lets not forget that a bullet can also drift to one side due to its spin and the gyroscopic resistance to being 'turned' nose first as it arcs downward.

quote:

... Angle of attack changes over distance, because Angle of attack is equal to the square root of the sum of yaw and pitch and yaw and pitch are not equal at all points on the trajectory ....

Oooh... boy! My heads hurts. I'll try again in the morning!

quote:

Originally posted by muck:
Here is a good read on the subject(external balistics). It is a bit long but full of info.
It explains some of the events being discussed.

http://www.nennstiel-ruprecht.de/bullfly/index.htm#Figures

muck

That's the one! A good read folks - quite long and detailed. That's where I got much of my info from.

Here is another one;

quote:

Lilja Precision Rifle Barrels - Articles: Uniform Rifling DepthIt is also quite likely that the bullet will begin to yaw while still in the barrel. This yaw will only become worse once the bullet leaves the barrel and ...
www.riflebarrels.com/articles/50calibre/uniform_rifling_depth.htm

quote:

The SMLE was known for this in target shooting.

The effect with the SMLE had to do with vertical dispersion at long range due to the variability in powder charge and bullet weight in the Radway-Green ammo they were shooting at the time. The armorers (Fulton was one as I recall) would adjust the bedding and stock flexibility so that a light bullet with a big charge and a heavy bullet with a light charge would arrive at 1000 yards at the same elevation. At intermediate ranges, the vertical dispersion was greater. It did nothing to affect horizontal dispersion.

Charles Young had a good article on the subject some years ago in Precision Shooting. He was pretty clear about the fact that this was only done to accomodate the poor ammo of the day and quirky nature of the SMLE. Given a choice, he would have gone for a purpose-built target rifle and carefully loaded ammo every time.

Example. I have a .308 that shoots 165-grain Accubonds into a three-inch group at 200 yards. Unfortunately, the same rifle shoots the same load into a 2-1/2 to 3-inch group at 100 yards!

No, it's not tighter at 200, but I theorize that the bullet is just starting to stabilize when it strikes the 100 yard target, and then holds true to 200.

The same rifle shoots much lower B.C., 150-grain Grand Slams into a 1 to 1-1/2 inch group at 100.

It's obvious that this rifle likes lower B.C. bullets.

/

OK, First of all a rifle isn't going to shoot 1" groups at 100yds and then smaller than 1" groups at 200. But they CAN and do shoot 1" groups at 100 and say 1 1/2" groups at 200 which is smaller groups in terms of MOA.

The way to explain it is that bullets do "Wobble" (I know there are more precise names) when they are coming out of the barrel. As they wobble they diverge (diverge meaning move away from the center path) at a certain rate. If they continued to wobble at the same rate the bullets would diverge at the same rate and the MOA sizes at long ranges would be roughly the same.
But Bullets do start to Stablize and smooth out their flight and stop "Wobbling" as much as the range increases. So as the bullets stabilize they diverge at a slower rate.
That's why you might shoot 1 MOA at 100 and 1/2 MOA at 300...............................DJ

quote:

....Remember that this is all supposed to be for fun!..................

This is fun!

On www.riflebarrels.com/articles/50calibre/uniform_rifling_depth.htm they talk of bullets that get worse down range.

JohnD, my uncle, who was an armourer, told me about the "properly packed" SMLE being very accurate at long range. He did also say that the accuracy improved down range due to the spiralling flight path dampening out i.e. not getting worse. But he could have been wrong, unless that effect was over and above the vertical spread. But he also mentioned bullets being selected for target use by rolling them on a ground and polished flat surface. So maybe he was not talking about Radway-Green ammo. He was in a different country (South Africa).

quote:

Originally posted by GAHUNTER:
Example. I have a .308 that shoots 165-grain Accubonds into a three-inch group at 200 yards. Unfortunately, the same rifle shoots the same load into a 2-1/2 to 3-inch group at 100 yards!

No, it's not tighter at 200, but I theorize that the bullet is just starting to stabilize when it strikes the 100 yard target, and then holds true to 200.

The same rifle shoots much lower B.C., 150-grain Grand Slams into a 1 to 1-1/2 inch group at 100.

It's obvious that this rifle likes lower B.C. bullets.

Umm, 1.5 MOA is (your 200yd groups) is tighter than your 3MOA 100yd groups. Shoot the same load at 300yd and see what you get (3" @ 300 would be a 1 MOA group).
To say it dosn't like the longer (high BC) bullets is kind of a misnomer, it does like them, just at longer distances than 100yd.

quote:

Originally posted by Reloader:
It seems that some shooters believe in the theory that certain loads can actually defy the laws of physics and shoot much tighter groups at longer ranges(IE 1.5 MOA at 100 and .5MOA at longer ranges). ....

Quoting from http://www.nennstiel-ruprecht.de/bullfly/index.htm
"Up to this point, we have only considered bullets at close distances from the muzzle. We have met well-designed military projectiles and over-stabilized pistol and revolver bullets, but all of them showed dynamic stability. In other words, the maximum yaw angle, which occurs close to the muzzle, is damped out as the bullet moves on. After a travelling distance of a few thousand calibers, depending on the damping rate, the transient yaw angle practically approaches zero. "

Fellas, you can actually watch the corkscrew through a good spotting scope when firing an S&W 29 with 240 gr bullets. I shot IHMSA for years and spotted for several friends using the S&W. These guns were very accurate shooting 1/2" groups at 50 yd's. But you can watch the bullet wind around the flight path and by 200 meters it is almost gone. Switching to a heavier bullet of 265 gr's and up would eliminate it. The effect was not seen in Ruger's, with all bullets running a straight course. (Not counting wind drift.)
One effect on paper was if you changed distance slightly for each group, the groups would wind around the paper too, but still each group was tight.
To carry this further, I owned a Model 70, pre 64 in .220 Swift. I shot a hot load with the Hornady 60 gr bullet. It had a Balvar 6 X 24 scope on it. I never, ever shot less then 1" at 100 yd's with it. However I had a pile of 5 shot 1/4" groups at my sight in range--350 yd's. This rifle head shot chucks to 600 yd's. I have never in my entire life had a rifle as accurate as it was and I plumb wore it out.
My friends have .22-250's and we have never seen this effect, groups just widen as distance increases. However the twist rate is slower in them.
I am convinced it is due to bullet length and twist rate. Bullets can and do go to sleep after a certain distance if spin rate and velocity creates a corkscrew effect.
I was pretty far out of the ball park with the 60 gr bullet in my Swift but it worked best at long range. Lighter bullets did not exhibit the trend but never did good way out there, groups would get larger.
In your normal range of loads and bullets, you will never see your gun shoot tighter as range increases. You have to be outside the box. I have never duplicated it.

My head hurts!! Good stuff!!!

Bfrshooter: I agree with the bullet wobble....I have seen 44s and 45s do this on IMHSA courses while spotting for others...to me it seemed to be most noticeable about 90 -100 yards out and continued to impact at 200 meters...creating a pattern at best and misses at worst if the wind shifted slightly...

I think also that I have seen this yawing when shooting a 7mm RM at about 65-70 yds on paper targets where the bullet seemed to keyhole but out at 200 yards there was no sign of keyhoing...just an observation...

quote:

Originally posted by David Antonucci:
My Kimber 8400 300wsm consistently shoots one inch groups at 100 yds and 1 inch groups at 200yds (1moa and .5moa). I'm not trying to start an argument, I'm just as confused as the rest of you

In this case perhaps you have a parallax issue which has corrected for 200 yards... The rifle should shoot better at 100!

quote:

Fellas, you can actually watch the corkscrew through a good spotting scope when firing an S&W 29 with 240 gr bullets. I shot IHMSA for years and spotted for several friends using the S&W. These guns were very accurate shooting 1/2" groups at 50 yd's. But you can watch the bullet wind around the flight path and by 200 meters it is almost gone.

quote:

Bfrshooter: I agree with the bullet wobble....I have seen 44s and 45s do this on IMHSA courses while spotting for others...to me it seemed to be most noticeable about 90 -100 yards out and continued to impact at 200 meters...creating a pattern at best and misses at worst if the wind shifted slightly...

Hey Guys! This very intersting thread just got more interesting! This is the 'proof' we have all been looking for!
Eye witnesses.

Thanks for that, bfrshooter and Gila Jorge.

And quoting from Woods ;

quote:

..... my "theory in progress". I haven't gotten any smaller groups at longer ranges but I have seen anecdotal evidence of the bullet groups moving from side to side. In other words, the group might be dead center at 100 yards, to the right at 200 yards and to the left at 300 yards. This is hard to document and state as fact because any wind has a profound effect at the longer ranges....

Alf 'explained' it ;

quote:

I believe that bullets fired from my rifles execute two basic motions when in flight.

Precession which is the slow corkscrew motion of the bullet and superimposed on this is nutation which is a fast rotating motion.

The nutation motion damps out over distance, between 60 or 100 m whilst the precession motion remains, that precession motion however changes over distance as well but not as pronounced as the nutation motion . The motion dimension as expressed in Pitch and yaw is small @ 200 m but then gets slightly bigger @ 600 to 1000m. .....

Great thread!

This is a repeat of another thread on the same subject. Sierra bullets verified that this does happen. Some bullets heavy for their diameter do give decreasing MOA with range.
You don't even have to believe me. Just call Sierra and talk to Paul Box 1.800.223.8799.
Of course if you know more about long range accuracy than Sierra call them anyway and straighten them out.
I have a 25-06 that does this BTW....
laughing here .....

Some subject on an earlier thread

No one ever called Sierra and reported back on the other thread. I was the last poster.