I heard that some long range bullets, loads like 190 gr. 308 , bullets in 300 win mag cal. Do not best stabilize until 200 or 300 yards...is this true with some long range loads?
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Advanced Marksmanship Is it true??
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As I understand it, each bullet design has it's own individual requirement for stabilization. with considerations to placement of ogive in relation to total length, balance point, length and angle of boattail, overall length of bullet in relation to rate of twist, muzzle velocity requirement for bullet to stabilize and probably other factors that enter into the equation. Some bullets "go to sleep" early in flight, some late. A lot "wake up" at distance. It takes a lot of experimentation and getting advice from others to find out which one is best for you rifle.
No,
bullets are dumb, there are no external forces that re-stabilize them 200 yards later. If they start out wrong, they stay wrong. They can't correct themselves, no wings, rudders or pilots.
What people mistake is the fact some shoot poorly when they can see what they are shooting and better when they can't, like 300 yards away. The human influence is huge, but you can't think a bullet stable.
Did you ever see a tumbling football right itself ?
bullets are dumb, there are no external forces that re-stabilize them 200 yards later. If they start out wrong, they stay wrong. They can't correct themselves, no wings, rudders or pilots.
What people mistake is the fact some shoot poorly when they can see what they are shooting and better when they can't, like 300 yards away. The human influence is huge, but you can't think a bullet stable.
Did you ever see a tumbling football right itself ?
Some bullets will 'weathervane', some won't; it's a matter of the relationship between the center of mass and the center of area. If they are the same (like a football, and some bullets)), they won't, if the CofM is sufficiently ahead of the CofA (like an arrow, and some other bullets), they will.
This is precisely like going to the top of a tall building, holding an arrow out horizontally, and dropping it. Does anyone really think it isn't going to land nose down? For the football, bets are off. Put a tail boom and feathers on that football, and you could probably get some takers.
While this, and many other truths exist, that does not mean that they will ride in to save the day.
Time of flight is damned short, and although forces on a bullet are not what one's intuition usually perceives (they are usually several orders of magnitude different from what we imagine. For example, the increase in aerodynamic force equals the square of the increase in velocity. I.e. the drag at 1000fps, a moderate bullet velocity at a 1000yd target, is a hundred times greater than the drag at 100fps, a moderate arrow speed. At 3000fps, it's nine hundred times.), these forces are at work the whole many yards to the target.
So, I think the answer is a reserved 'yes', but I also think it's a very small 'yes'. It could happen, but there may not be enough time before impact for it to happen in a significant way.
As a thought exercise, let's contemplate that a long trajectory follows a rather pronounced arc. If bullets didn't 'weathervane', how could it be that properly stabilized bullets leave round holes? There is a force at work, there has to be, and it's aerodynamics.
BTW, there is a real thing called overstabilization.
When gyroscopic stability drastically outweighs aerodynamic stability, the bullet will not align with the trajectory curve. Far along that curve it will strike the target at an angle that does not conform to that curve. The bullet hole will be elongated, and appear to be a keyhole, but it is not. The differences (from a true keyhole caused by insufficient gyroscopic stability) will be that the drop will be accentuated (due to increased yaw-induced drag), the 'points' of the holes will be similarly oriented (usually 'up'), and dispersion will not be especially greater. I've actually caused and seen this. This is a relevant reason why Palma barrels need a slower twist.
The key overall issue to this question is that there are two kinds of stability at work here; static (gyroscopic) stability, and dynamic (aerodynamic) stability. Without a significant difference between CofA and CofM, dynamic stability is not going to be any kind of helpfully significant issue.
Greg
This is precisely like going to the top of a tall building, holding an arrow out horizontally, and dropping it. Does anyone really think it isn't going to land nose down? For the football, bets are off. Put a tail boom and feathers on that football, and you could probably get some takers.
While this, and many other truths exist, that does not mean that they will ride in to save the day.
Time of flight is damned short, and although forces on a bullet are not what one's intuition usually perceives (they are usually several orders of magnitude different from what we imagine. For example, the increase in aerodynamic force equals the square of the increase in velocity. I.e. the drag at 1000fps, a moderate bullet velocity at a 1000yd target, is a hundred times greater than the drag at 100fps, a moderate arrow speed. At 3000fps, it's nine hundred times.), these forces are at work the whole many yards to the target.
So, I think the answer is a reserved 'yes', but I also think it's a very small 'yes'. It could happen, but there may not be enough time before impact for it to happen in a significant way.
As a thought exercise, let's contemplate that a long trajectory follows a rather pronounced arc. If bullets didn't 'weathervane', how could it be that properly stabilized bullets leave round holes? There is a force at work, there has to be, and it's aerodynamics.
BTW, there is a real thing called overstabilization.
When gyroscopic stability drastically outweighs aerodynamic stability, the bullet will not align with the trajectory curve. Far along that curve it will strike the target at an angle that does not conform to that curve. The bullet hole will be elongated, and appear to be a keyhole, but it is not. The differences (from a true keyhole caused by insufficient gyroscopic stability) will be that the drop will be accentuated (due to increased yaw-induced drag), the 'points' of the holes will be similarly oriented (usually 'up'), and dispersion will not be especially greater. I've actually caused and seen this. This is a relevant reason why Palma barrels need a slower twist.
The key overall issue to this question is that there are two kinds of stability at work here; static (gyroscopic) stability, and dynamic (aerodynamic) stability. Without a significant difference between CofA and CofM, dynamic stability is not going to be any kind of helpfully significant issue.
Greg
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Most if not all bullets "yaw". Some handle it better than others. Gyroscopic force is very powerful. If the jacket is not uniform or it loosens from the core, there is no hope for recovery.
What is trying to be described is two things here...
That by "going to sleep" they will see better accuracy at 300 yards than they see at 100 yards... and being stable means perfectly round holes all the way through.
Accuracy this way is angular, if you put rice paper at 100 yards with your bullet that "goes to sleep" at 200, and then shoot through one so you can see it, while you measure on the other. How does the bullet come back on course to be accurate at 300 by not at 100 ? Does the angle bend back on itself ?
Over-stablizing and yaw are different than the idea of bullet going to sleep. That creates issues and sure they may not sure up until later, like having a bullet fall apart in flight or keyhole at the target, but neither of those are gonna be "accurate" due to the unpredictable nature of it.
Now, you can have a person shoot a group at 100, and do poorly and then move to 300 where they can't see the group and do better. That has been seen, but if the bullet is passing through both 100 and 300 yard targets how does it come back on course ?
If you put the wrong bullet in a rifle with the wrong twist to effective stability, you are not gonna find a place it is accurate. Stability combined with accuracy is determined very early, it doesn't happen much letter like 200 yard away.
That by "going to sleep" they will see better accuracy at 300 yards than they see at 100 yards... and being stable means perfectly round holes all the way through.
Accuracy this way is angular, if you put rice paper at 100 yards with your bullet that "goes to sleep" at 200, and then shoot through one so you can see it, while you measure on the other. How does the bullet come back on course to be accurate at 300 by not at 100 ? Does the angle bend back on itself ?
Over-stablizing and yaw are different than the idea of bullet going to sleep. That creates issues and sure they may not sure up until later, like having a bullet fall apart in flight or keyhole at the target, but neither of those are gonna be "accurate" due to the unpredictable nature of it.
Now, you can have a person shoot a group at 100, and do poorly and then move to 300 where they can't see the group and do better. That has been seen, but if the bullet is passing through both 100 and 300 yard targets how does it come back on course ?
If you put the wrong bullet in a rifle with the wrong twist to effective stability, you are not gonna find a place it is accurate. Stability combined with accuracy is determined very early, it doesn't happen much letter like 200 yard away.
My "give a crap" is on the blink so what I say is useless most of the time. I have a 50 that shoots 1 1/2" to 2" at 100 but 8" to 12" at 1000 is common. Does better if a marksman shoots it. Could be the "not being able to see the target" thing but you're going to have to twist my arm.
Why does the rear sight on a Trapdoor Springfield elevate at an angle? My guess is it's a velocity twist rate issue.
Why does the rear sight on a Trapdoor Springfield elevate at an angle? My guess is it's a velocity twist rate issue.
It is a combination of things with the Springfield.
mostly because a heavy, poorly designed bullet is flying pretty darn near subsonic and it is being lobbed. Is it right, maybe, hard to say when you consider the accuracy window of it. But where that angle of the sight has an effect, the bullet is moving very slow. No longer supersonic so it will drift.
The .50, I would say is perception, up close you see the effects of recoil much more so than shooting it at a far target. And you mind is fixated on the 100 yard group.
mostly because a heavy, poorly designed bullet is flying pretty darn near subsonic and it is being lobbed. Is it right, maybe, hard to say when you consider the accuracy window of it. But where that angle of the sight has an effect, the bullet is moving very slow. No longer supersonic so it will drift.
The .50, I would say is perception, up close you see the effects of recoil much more so than shooting it at a far target. And you mind is fixated on the 100 yard group.
I agree completely that I shoot better when I don't see the bullet holes (scoring shots, as opposed to sighting shots). My biggest 'shooting negative' is my failure to heed my own advice about not touching the turrets once going from sighters to score targets. I would estimate that accounts for about 70-80% of my dropped points in F Class comps.
Greg
Greg
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Thankyou, I believe that I will not dwell on this statement made by an f class shooter...I am going to trash it as virtually useless info...
Mind blown... that totally makes sense. Thanks for that bit of insight. My physics sense was never comfortable with the settling in thing, and this explanation fits well.
I'm on the fence on this. I understand the logic but I don't "see" the holes on the target when I'm shooting groups. My focus is on the aiming point.
I like to have my bullet impact high or some f'n place besides where I'm aiming. If you shoot your aiming point, what are the odds of shooting a tighter group?
I like to have my bullet impact high or some f'n place besides where I'm aiming. If you shoot your aiming point, what are the odds of shooting a tighter group?
I remember reading a study done around WW2 on the .303 Brit cartridge where it was proven that the round was more accurate at some longer distance (500ish yards if I remember right) than at 100 yards. I don't remember how they tested it but the study was lengthy and it stuck with me as that was the first time I had heard it and 'saw' it proven.
Besides that however, I have no reason to believe that there is a 'sweet spot' as far as stabilization and accuracy other than when the round destabilizes.
Besides that however, I have no reason to believe that there is a 'sweet spot' as far as stabilization and accuracy other than when the round destabilizes.
The yaw vs pitch does come into play here. Imagine it putting the bullet into a slight circular motion. That circle becomes tighter as the forces stabilize. Sometimes this doesnt optimize until after 100 yards. That is why sometime you will see better accuracy at different distances.
It doesn't make sense unless you think about the bullet traveling in a slight helical motion that tightens up over distance for some bullets. Most people don't consider the helical motion which is why it seems impossible to them.
These are not new questions here, nor new explanations. Many of us have been to this point and then progressed further. It is a natural progression to research the subject, uncover interesting details, and dwell on them. But fulfillment requires taking all things into account, weighing their significances, and endeavoring to winnow out the chaff. In the end, fulfillment is a process that seeks simplicity.
Do these phenomena exist? Absolutely!
Do they exist to the extent that one should not be embarrassed about losing sleep over them? Probably not.
They are interesting details, but the overall scheme, getting hung up over them simply delays fulfillment.
If you're missing the target, it's probably you, and not something about the gun, or the environment, or the Moon being in the Seventh House, that you should be blaming. Excuses exist, but the more valid ones are more often about the shooter, and not the rest of the system. Bad gear exists, but putting it into another's hands often uncovers the real problem.
Greg
Do these phenomena exist? Absolutely!
Do they exist to the extent that one should not be embarrassed about losing sleep over them? Probably not.
They are interesting details, but the overall scheme, getting hung up over them simply delays fulfillment.
If you're missing the target, it's probably you, and not something about the gun, or the environment, or the Moon being in the Seventh House, that you should be blaming. Excuses exist, but the more valid ones are more often about the shooter, and not the rest of the system. Bad gear exists, but putting it into another's hands often uncovers the real problem.
Greg
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I get what you're saying. But in defense of the original question (which wasn't mine, but is one I've heard a good bit), if there was a potential phenomenon that made your groups 2MOA at 100-300 yards, but 1MOA at 300 and beyond (exaggerated for clarity!), it would have significant implications for things like load development (esp. if you can't develop loads beyond 100). I've been mystified by some of the so-called expert commentary I've seen in the past about bullets going to sleep, and this discussion has added clarity for me.
Thanks!
Nope. I disagree.
When does this "helical motion" start? All rounds are leaving the muzzle at the same exact point on the start of their ballistic path. Each round would have to "grow" your helical motion into a max circular path and then shrink it back into the original ballistic center at some time downrange.
How does a dumb projectile know where the original path was?
According to barrel makers and bullet makers, the bullet is at its most pristine and optimal stabilization immediately after leaving the muzzle. Also the bullets RPM rate does not degrade in proportion to its velocity drop. The RPMs do not decay near as much in relation to distance.
In my opinion, you can work up a "1000 yd" load with a 100yd target and a chronograph. Small groups and low ES/SD will not change over distance when you take all environmentals out of play.
I helped map out a 50 Cal. Qual course for a federal agency about 4 years ago. They had a sudden and specific potential need arise for anti vehicle capability at high angles and with max range of 200yds. When I arrived, some of the senior guys had already been on the INTERNET and found that we were fucked because 50s don't stabilize until at least 500 yards.
I told them that was awesome and we went on out to the range complex. We shot nice SMALL round groups at 50, 100 and 200 yards with some off brand ball and some high dollar AMAX target rounds. Guns were 2 McMillan bolt guns and one Barret M105 with some dicked up springs. At first it was mostly the noise of crickets when the first shots were fired at 50yds...... then they were all bitching about the INTERNET! Finished ironing out the times, targets and procedures for their qual and they went away with a new view on things.
Once a projectile leaves its intended path (that which would put all of them in one hole), there is no way it can know where the original path was and return to it, then remain on it for the remainder of its flight.
I'm not a ballistician but I have watched a shit load of Star Trek in the 70's.
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Related to the video linked in the post above, Bryan Litz wrote an article about the phenomenon of groups being angularly smaller at distance. Don't think he proved or disproved it, but he did show "that if the phenomenon actually happens, epicyclic swerve is not the cause of it."
Link: Epicyclic Swerve
Perhaps he will chime in on this thread.
Link: Epicyclic Swerve
Perhaps he will chime in on this thread.
That is NOT a Video, but a computer simulation, to describe an outcome to prove a persons point by same person who wrote the program... and it's all happening even in the simulation, inside 100 yards. Not beyond.
It's a guess... simulated by a computer with the variables given to it by a person, and as noted, even Bryan says, this is not an indication of the cause.
It's a guess... simulated by a computer with the variables given to it by a person, and as noted, even Bryan says, this is not an indication of the cause.
The helical path of the bullet is a real thing that is pretty well understood, and it can certainly shrink with distance.
But the radius of that helix is also *tiny* - like a few thousandths of an inch and it's not easy to predict or understand in a practical sense. In other words, it's not worth worrying about.
But the radius of that helix is also *tiny* - like a few thousandths of an inch and it's not easy to predict or understand in a practical sense. In other words, it's not worth worrying about.
As (The German) pointed out there are anecdotal observations of groups getting tighter? We have all heard these stories. This is seemingly paradoxical to our understanding.
Best guess here.
In reading the Mr. Litz's comments he seems to be running a simulation that stipulates a possible oscillation in a barrel (I'm guessing) thus creating rift between center axis of a bullet and the center axis of the barrel. Perhaps some transverse force (vibration, concentricity error, some physical manifestation) induces a theoretical yaw in the simulated projectile. He goes on to say in theory a thicker stiffer barrel the less variation in those two alignments? As well he goes into some details about rotation values of the projectile? I don't know if people are making the link between accuracy/stability and this phenomenon?
I think it has been said, but the longer a bullet is in flight the weaker it's energy (quadratic or exponential loss) then the more external forces can act upon it. So down range stabilization/accuracy becomes less likely. It's a game of (aerodynamics vs. inertia and torque). Perhaps this is obvious to everyone? I am just thinking out aloud.
And as someone wisely pointed out it's almost completely academic and of no real concern to us. Mr. Cross somewhat empirically proves this point with a .50 cal.
None the less a curiosity that makes for a very interesting thread.
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This isn't possible. There are a bunch of factors that go into the inherent accuracy of a bullet (actually, a weapons system), but those factors are effectively fixed. Insofar as they do change, because of heat warping or other physical phenomenon, they do not increase the inherent accuracy of a bullet. I'm almost willing to bet that any increase in accuracy is entirely dependent on the psychological impact of expectation. Within short engagement ranges you can directly and clearly see points of impact, not to mention the fact that most consider anything inside 100 yards/meters to be an easy shot with a rifle, so there is the added stress of living up to a perhaps overblown expectation. At 500 yards/meters you're shooting for center mass, so psychological expectation is greatly reduced and you become closer to the zen-like state necessary to make a perfect shot.
tl;dr - It's not the bullet, it's the shooter.
Yep, and just like with a football the complete absence of helical spin actually hurts accuracy.
Well, the difference with a football is that there are times where a transverse force is inadvertently applied to the ball when it leaves the hand, this is from the fingers or thumb. The ball actually will correct it's self if it's spinning fast enough and rotate more true along it's long axis. In a perfect world gyroscopic force stabilizes the ball immediately and there would be no yaw/variation in it's orientation or along it's long axis.
In the footballs case helical rotation is of more concern than to a shooter.
So, the helical/corkscrew rotation if great enough would hurt stability/accuracy by creating non laminar air flow across the balls surface. Where a perfect gyroscopic rotation would create the centrifugal force needed to keep the ball aerodynamically true and on it's intended trajectory.
Two different things.
As well, this is different than what Frank is talking about when a ball starts to destabilize along it's path. In which case (as stated) it's impossible for the ball to re correct itself.
I do see your point about the accuracy being greater at longer ranges due to psychological effects, perhaps this could be true?
I don't disagree. There was a Sports Science segment on ESPN that basically discussed this topic and the point was brought up that a very small amount of wobble help keep the football on its intended arc, but a wounded duck is just that. In a bullet the wobble is so small as to be all but immeasurable.
I don't see why it wouldn't be, the opposite certainly is true. A rifle doesn't shoot 1 MOA groups at 100 meters and then decide it's going to shoot 5 MOA groups at 1,000 meters; that's the flaws in a shooter's technique revealing themselves. An important point to consider is if the soldiers involved in the study knew it was effectively a test, as that would certainly amp up the stress level.
We are the usually the most complex and flawed variable to a weapon system or instrument for that matter.
try to put any rifle w.any load in the steady hands of the fictional "PERFECT" shooter, or on a "PERFECT" lead sled,if exist, or on the Cruiser/unlimited br class, even with ol'style string-activated trigger...
the Group will never print tighter at the increasing of the target/bullseye/steel distance_
the Group will progressively,if not exponentially, open up at the increasing of the distance_
(I can't bet about the existence of God or Devil, but I can bet that the Group,with any bullet,any load,any sights,or no sights at all, WILL PRINT LARGER ON THE TARGET WITH THE GROWING OF THE TARGET's DISTANCE, approximately with an ice-cream cone shape with the pointed end at the muzzle of the same rifle,handgun,mg or even AA cannon) _
the Group will never print tighter at the increasing of the target/bullseye/steel distance_
the Group will progressively,if not exponentially, open up at the increasing of the distance_
(I can't bet about the existence of God or Devil, but I can bet that the Group,with any bullet,any load,any sights,or no sights at all, WILL PRINT LARGER ON THE TARGET WITH THE GROWING OF THE TARGET's DISTANCE, approximately with an ice-cream cone shape with the pointed end at the muzzle of the same rifle,handgun,mg or even AA cannon) _
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I haven't seen groups get tighter, but I have seen smaller moa groups at further distances. For example, 100-yard groups might be 0.75" (or ~0.75 moa), while 200-yard groups will run 1.25" (or ~0.625 moa) and 600-yard results can be 4" (or ~0.667 moa). Some will claim that it's the shooter because the target and bullet holes are not as easily seen, but I just don't buy it when the targets are purposely sized proportionally based on distance, and holes in paper (or splats on steel) are viewable through the scope. The phenomenon seems more common with longer heavier higher-BC bullets.
This was really the premise of Litz's article. It wasn't that bullets print smaller groups at distance, but rather that groups are angularly smaller. He acknowledges that many shooters have observed the occurrence, and admits to seeing it himself. He didn't prove or disprove the existence, but proved that if it does exist, it's not due to epicyclic swerve.
Epicyclic Swerve
This was really the premise of Litz's article. It wasn't that bullets print smaller groups at distance, but rather that groups are angularly smaller. He acknowledges that many shooters have observed the occurrence, and admits to seeing it himself. He didn't prove or disprove the existence, but proved that if it does exist, it's not due to epicyclic swerve.
Epicyclic Swerve
Frank,
You've probably got a lot more authority on this subject than I do, but I've been arguing that point for years at the range... there's no logic behind the idea that a bullet will be out of control and inaccurate at a close distance, then suddenly become controlled and accurate further down range. The concept simply defies physics, and geometry. I hear people saying things all the time that come out like: "Oh, this load only shoots 3 inch groups at 300 yards, but will shoot 2 inch groups at 400 yards". I wish they'd think about that statement and realize how inherently flawed it is.
There's a lot of science going on here that I probably don't even understand, but the simple fact remains that a bullet doesn't get more accurate as distance increases.
Lets also consider what constitutes a good group at different distances. If you want to stack rounds on top of one another and in your mind half moa is a good group, the requirements are different.
At 100 yards putting 5 rounds under a half inch requires a good handle on the fundamentals. At 300 yards on a calm day with a 3ish mph wind there isn't much flight time for wind to come into play yet. If you hold off a bit now you only have to put 5 inside an inch and a half to pat yourself on the back. The flight time is still pretty short but the requirements for beers and bragging have essentially tripled.
It seems to take more time, 500-600+ yards before there is enough environmental influence to catch up to the MOA shooting standard and make people have to utilize a skillset to maintain tighter accuracy requirements at distance.
Just my opinion and I've been wrong before.
At 100 yards putting 5 rounds under a half inch requires a good handle on the fundamentals. At 300 yards on a calm day with a 3ish mph wind there isn't much flight time for wind to come into play yet. If you hold off a bit now you only have to put 5 inside an inch and a half to pat yourself on the back. The flight time is still pretty short but the requirements for beers and bragging have essentially tripled.
It seems to take more time, 500-600+ yards before there is enough environmental influence to catch up to the MOA shooting standard and make people have to utilize a skillset to maintain tighter accuracy requirements at distance.
Just my opinion and I've been wrong before.
To a degree, accuracy is still just probability... obviously the more craftsmanship that goes into a weapon and the higher the grade of components used, the better the results, but it is impossible to predict a bullets EXACT path to the .000 decimal place. Be it barrel harmonics, flex in the action, if the weapon is allowed to free-recoil back, not to mention the weather conditions... one never will predict the exact flight. Being that conditions change from shot to shot, and because there are so many variables it is essentially probability to a limited extent, so it is possible for some lucky shots to exist that give the appearance of tightening up groups at distance. Obviously there is no science involved with this explanation... and probability is most likely too unacceptable to be an explanation for most pallets, but it is possible.
Yes, it does exists, but I think we need to put that into some perspective. Overstab is one of those things that are highly "overemphasized" (no pun intended). The OverStab condition is indeed not a bad condition in itself, and is greatly exaggerated in terms of its ill effects, since most if not all bullets start in an overstab state that dumpens itselfs downrange.
